Why women choose divorce: An evolutionary perspective

In Western dual-educated, male-female marriages, women who divorce face greater burdens because of decreased income and primary or sole responsibility for caring for children than men who divorce. Why, then, do these women initiate divorce more and fare better psychologically after a divorce than men? Here, we articulate an evolutionary mismatch perspective, informed by key findings in relationship science. We argue that mismatches between women’s evolved preferences and configurations of modern marriage often clash, producing dissatisfaction. Women’s unprecedented career ascendance also affords women ever more freedom to leave. We discuss pressures from social expectations for men and women that contribute to or compound these vulnerabilities. We conclude with key questions for future research, which can contribute to strategies for mitigating relationship dissatisfaction and the profound loss and pain that results from divorce. Addresses 1 University of California, Los Angeles, Department of Communication, 2225 Rolfe Hall, Los Angeles, CA, 90095, USA 2 Rutgers Business School—Newark and New Brunswick, 1 Washington Park, Newark, NJ, 07102, USA 3 Texas Christian University, Department of Psychology, Winton Scott Hall Suite 246, 29955S University Drive, Fort Worth, TX 76109, USA 4 University of California, Los Angeles, Department of Psychology, 502 Portola Plaza, Los Angeles, CA, 90095, USA Corresponding author: Haselton, Martie G. (haselton@ucla.edu) 1 Here our focus is on marriage between Western men and women, which is important to examine because women’s and men’s evolved desires differ and can clash. Current Opinion in Psychology 2022, 43:300–306 This review comes from a themed issue on Separation, Social Isolation, and Loss Edited by Gery C. Karantzas & Jeffry A. Simpson For a complete overview see the Issue and the Editorial Available online 31 July 2021 https://doi.org/10.1016/j.copsyc.2021.07.02


Introduction
When people choose to get married, typically they do so with the intention of staying together forever d 'till death do us part.' Nevertheless, roughly half of marriages in the US end in divorce [1]. This is costly to all involved, particularly to women.
Post-divorce, within Western heterosexual couples, women experience a significant decrease in income compared to men [2,3], and their risk of falling below the poverty line skyrockets [4]. 1 In contrast, Western men's income decreases modestly [2,3] or increases [4]. Women often take sole or primary custody of children [5] and are less likely to remarry [6,7]. Therefore, divorce involves a compound burden for many women, juggling both paid labor and most of the unpaid childcare work with fewer resources than are typically available to divorced men. Despite these costs, women are more likely to initiate divorce [8,9] and report greater life satisfaction post-divorce [10,11] than men. This represents a paradox of contemporary, Western divorce. Given the greater costliness of marital dissolution for women, why are women more often its initiators and psychological beneficiaries?
Provisional answers exist in literature showing that physical abuse [12], financial problems [13,14], infertility [15], infidelity [15,16], and personality conflicts [17] contribute to divorce. Although it is important to understand relationship-level variables that can cause relationships to erode, which is typical in the literature, it can obscure the fact that divorce typically does not occur because a relationship falls apart; instead, it typically occurs because one partner decides to leave [18,9]. In addressing why women initiate divorce from men, we need to understand individual-level factors that differ between men and women.
Here, we use insights from evolutionary and relationship science to examine this paradox of woman-initiated divorce. We propose that women's unprecedented professional ascendance has created mismatches between women's evolved preferences and modern marriage. Although women's professional success has helped emancipate them politically and economically from men, it also makes women and men less interdependent, changing the benefits of marriage and the costs of dissolution. This perspective leads to new research questions. We posit that answering these questions will help to identify means of improving relationships by minimizing gaps created by mismatches.
Women in the workplace: a new feature of the modern world Ancestrally, pregnancy and childcare are likely to have kept women close to home. This created a dependency for women on a partner's provisioning (e.g. food, shelter, other resources). All of our female ancestors were mothers, and motherhood was virtually guaranteed to sexually active women. Motherhood and dependence on men, for our female ancestors, were not choices that women had to make. Instead, they were simply a part of life.
Today, things are different. Women can control their fertility, plan families, and achieve professional goals. Women earn 57.3% of bachelor's degrees, 60.1% of master's degrees, and 53.5% of doctoral degrees [19] and makeup 51.5% of the paid workforce [20]. When women have the opportunity to support themselves and not depend on men, many take that path.
Women's participation in the paid workforce benefits individual and collective well-being. Women's earnings are linked with greater life satisfaction [21,22] and better health [23]. Having women as part of an economic talent pool also increases company earnings and shapes innovation [24]. However, women's workforce participation has also created a dramatic shift in their relationships with men. For millennia, women were dependent on men's provisioning for survival and reproduction, and now they are not.
Here, we seek to detail how mismatches and other rapid social changes can contribute to women's decisions to divorce. We are not arguing for a shift back to traditional gender roles d instead, we see opportunities to modify relationships in ways that can be helpful in reducing relationship conflict and promoting relationship harmony. We view this article as a starting point for understanding new sources of marital discord and considering possible solutions beneficial to women and men.

Challenges created by evolutionary mismatches and eroding interdependence
Mate preference mismatch Preference for resources Abundant evidence shows that women prefer mates who can assist them by providing resources. In the modern world, these resources are largely monetary [25e27]. For example, one recent study of over 14,000 respondents across 45 countries highlights the robustness of a sex difference in women's preference for financial resources [27]. Regardless of country-level gender equality norms, women reported a higher preference for a long-term partner with good financial prospects than did men. In addition, recent US census data from over 55,000 participants suggest that these preferences guide mating decisions d income is positively related to the likelihood of getting married for men, but not for women [28]. As women's career success accelerates and men's remains constant or declines [29], fewer men will satisfy women's desire for partners with higher professional success than themselves.
Women's preference for status and resources likely reflects long-standing obligatory contributions to reproduction. For each pregnancy, women invest a minimum of nine months and a total energetic cost of nearly 80,000 calories; after childbirth, breastfeeding increases caloric needs by a non-trivial 26% [30]. Such energetic costs, coupled with mobility restrictions created by these activities, meant that ancestral women were dependent on others, typically the fathers of their offspring, for provisioning. Accordingly, women are hypothesized to have inherited from their successful female ancestors a preference for high-status partners who can provide resources to themselves and their offspring [31,32].
Given women's preference for partners who earn more than they do [28], what happens when women out-earn men? This question grows in importance as the wage gap closes for skilled workers [29], with women now outearning their husbands 22.1% of the time [33].
Although there is relatively little data on the relationship between relative financial contributions and relationship satisfaction, a large-scale longitudinal study (N = 12,000 Australians) showed that, within couples, a shift over time toward women out earning their partners was associated with decreases in relationship satisfaction for both women and men [34]. Examples of dra-matic shifts in women's status are consistent with this pattern: women who win major political elections are twice as likely to divorce compared with their counterparts who lose these contests [35] (See Box 1).

Preference for indicators of good genes
In addition to desiring partners with resources, women also desire attractive partners. In particular, women value qualities, such as symmetry, facial attractiveness, Box 1. Windfall gains in professional status and divorce.
What happens to marriages when wives or husbands make large gains in professional success?
A recent study examining Swedish register data from 1979 to 2012 shows trends in divorce following winning elections for political office or becoming a CEO [25].
The study included women (n = 641) and men (n = 1246) who ran for a parliamentary seat or as mayor. These offices are high in status and offer high incomes in the top 5% of the Swedish earnings distribution.
The left panel of Figure 1 shows that women elected to office experienced a sharper decline in remaining married, whereas the decline in remaining married was less steep for women who ran and were not elected. The right panel of Figure 1 shows that men who won versus lost their bid for election showed no difference in declines in remaining married.
The researchers also examined trends following being hired as a CEO from 2002 to 2012 (n = 105 Women; n = 715 Men). The resarchers were only able to examine data on CEO hires (and not those who applied but were not hired). Nonetheless, the trend is consistent with winning political office. Women hired as CEOs showed a greater decline in remaining in their marriages than men who were hired as CEOs.
The authors of the study considered a variety of different mechanisms that might explain their findings.
Are women who gain positions of high status more tempted to remarry? As women enter male-dominated professions, might there be more temptation due to the number of additional male colleagues these women have? This seems unlikely. Women who were elected or promoted to CEO were no more likely to remarry than the other groups: 22% of women who were elected/promoted and divorced, remarried compared with 27% of men who were elected/promoted and got divorced and 30% for divorces of both men and women who were not elected/promoted.
Are 'traditional' marriages more at risk? The authors examined age differences (women 4 or more years younger than spouse = traditional) and share of parental leave (>90% of leave taken by woman = traditional). Using these measures, more traditional marriages were more likely to break up when women were elected to office or promoted to CEO. The authors speculate that it is a violation of the expectations of the partners that drove divorces, when the marriage shifted toward a non-traditional female role, one or both parties were dissatisfied. masculinity, and social dominance, and seem to particularly value attractiveness, as indicated by at least some of these features, during times of high fertility within the cycle [36,37]. These features are purported indicators of good genes (i.e. health, physical resilience [36]). Evolutionary scientists have hypothesized that women value them because of the survival and reproductive benefits these features or their correlates would have afforded their offspring in challenging ancestral environments (Gangestad et al. in press).
Women's preference for good genes may produce another mate preference mismatch. The evolved preference for indicators of good genes is an adaptation that likely pre-dates adaptations for pair bonding [38]. Because not all men possess all the qualities that women desire, women often make tradeoffs, opting for one set of features over others. When women emphasize indicators of good genes, they may find that they are dissatisfied with their partner's provisioning. Indeed, men who possess purported indicators of good genes tend to be more oriented toward short-term mating and less well-suited as long-term partners who provide for partners than men who lack these features [39]. Accordingly, women who trade off resources for indicators of good genes may ultimately choose to leave those relationships, particularly if women can support themselves financially.

Caregiving mismatch
Women's obligatory investments in offspring likely forged a stronger desire in women than men for caregiving, contributing to a reluctance to relinquish caregiving to spouses [40,41]. Moreover, despite women increasingly working outside the home, women contribute 35% more childcare than did mothers in the 1960s [42,43]. This pattern even applies to women who earn more than their husbands, who often take on yet more childcare and housework than those who earn less. This hints that many professional women feel pressure to uphold traditional roles within their marriage [44].
Social norms surrounding the division of labor within households clearly have not yet caught up with the world of dual-income partnerships [45]. In one study of heterosexual married couples with female breadwinners (i.e. providing 80e100% of household income), only 38% reported that the wife was the primary breadwinner [46], suggesting a reluctance to admit counternormative earning. Consistent with this, stay-at-home fathers dedicate most of their time at home to masculine-typed housework, such as yardwork [47], leaving much of the rest, such as daily cooking and cleaning, for women.
Women's compound workload is a substantial stressor, the effects of which are linked to lower well-being and sexual desire for both partners [34]. In one study of 705 married women with children, women who took on more housework than men experienced lower levels of sexual desire for their partners, an effect mediated by women's perceptions of their partners as dependents [48]. This suggests that part of caregiving involves providing for the needs of male partners that can be similar in kind in providing care for children.
Role strain also has negative effects on men. Men who take time away from work to care for family (e.g. request family leave) or a role as a stay-at-home-dad are judged less competent by others compared with men who do not [45]. Men who work but do more caregiving than their peers experience coworker harassment and are deemed not assertive, strong, or ambitious enough [49]. The co-occurrence of women being under higher dualrole stress and men feeling social pressure to contribute to more male-than female-typed labor creates a quandary in relationships. If women perceive themselves as 'doing everything,' the benefits of a marital partnership are diminished.

Further insight from relationship science: decreasing interdependence between partners
With women's greater earnings comes less interdependence between partners. This could change women's willingness to tolerate annoyances in their marriage by altering their welfare trade-off ratio (i.e. the willingness to sacrifice personal welfare to increase partner's welfare [50]). This framework predicts that many women will be less willing to tolerate unsatisfying treatment from their partners d and more willing to escalate conflicts d because they are in a better position to walk away.
Moreover, a decrease in interdependence negatively affects relationship commitment [51,52], which can lead partners to disengage from processes that sustain Are divorces due to women's increased financial independence? Women who won elections and positions as CEOs already had high earnings (66% of the household income before winning). Therefore, economic independence alone, which was already high in women in these couples, is unlikely to have driven divorces.
We suggest that a key factor driving divorces in these data is a violation of women's preference for higher professional status in mates relative to their own, which is underscored by winning these high-status positions [27].
relationships [53]. When positive illusions about a partner's good qualities fade, for instance, the likelihood of relationship dissolution increases [54,55].
We acknowledge that the logic we outline here addresses the paradox of woman-initiated divorce in the Western, educated context. Importantly, the insights we offer likely do not apply at low-income levels, as partners are heavily interdependent, even if dual earners.

Working toward solutions
In sum, a loss of interdependence, along with evolvedpreference mismatches, pose threats to modern marriage. Before solutions, we need research to address gaps in the literature. We suggest that answering questions in four key areas will help.

Undoing gendered norms
First, conflicts over unpaid labor stem in part from gendered norms that differ by sex d for example, women are caregivers and men are breadwinners. Can associations between type of labor and masculinity and femininity be lessened? Messaging campaigns that reframe these activities could help to increase women's and men's comfort with counter-normative work and satisfaction in counter-normative marriages.

Childcare assistance
Second, if gendered associations with paid and unpaid labor prove difficult to undo, might assistance with childcare be a better or more immediate solution? Research should address whether this solution challenges gender norms less and the extent to which it reduces the burden on mothers, potentially producing greater satisfaction in marriages in which women are major or primary breadwinners. Assistance could be hired, provided by employers, or provided by the government, which is growing in political popularity [56]. In some instances, help could also come from extended kin, particularly grandparents, who have a vested interest in the happiness of their children and the success of their grandchildren. Without assistance, many women will continue to feel pressured to do double-duty or attempt to have their male partners help d but with tasks that men do not prefer, potentially damaging the satisfaction of both partners.

Agreements about specializations and interdependence
Third, households, such as organizations, could run more efficiently when each person specializes in, rather than shares, a type of labor [57]. With specialization can come greater interdependence between partners d each needs the other for the family to succeed. Research should address whether couples can be more explicit about the division of labor and whether this enhances interdependence, producing positive relationship maintenance processes.

Meta-knowledge about mismatches
Finally, can knowledge of evolved psychology allow partners to recognize that pangs of dissatisfaction are 'ancestral relics' and reframe them in ways that are less harmful to relationships? This is a question whose answer might have broad relevance to other evolutionary mismatches, including those that can occur in the realm of romantic relationships (e.g. casual sex [58]) and wellknown mismatches between evolved preferences for foods with high levels of sugar, fat, and salt and preserving good health. We see this as a particularly intriguing question and a priority.

Conclusions
In conclusion, we have argued that understanding evolutionary mismatches and a loss of interdependence between partners helps to resolve the paradox of woman-initiated divorce. We have suggested a number of possible ways that modern families can cope with the complications that arise from rapidly changing family structures. In our view, the research questions we outline are exciting avenues for exploration. These may ultimately be critical for understanding and preventing the profound sadness and loss that comes from the end of marriage [59] 10.1017/S0140525X00023992] As in the classic study, on average, women preferred good financial prospects in a mate more than men and older age than themselves, and men preferred good looks more than women and younger age than themselves. Greater gender equality within countries predicted smaller preferred age gaps within couples but did not predict sex differences in preferences for resources or attractiveness, inconsistent with the rival "biosocial role" theory. 28 * * . Hopcroft RL: High income men have high value as long-term mates in the U.S.: personal income and the probability of marriage, divorce, and childbearing in the U.S. Evol Hum Behav In press. The authors analyzed 2014 Census data from over 55,000 adults. Findings included: Men with higher income are less likely to be childless, more likely to marry, less likely to divorce, and more likely to remarry. In contrast, there was no relationship between women's income on their likelihood of marriage. High income women were more likely to divorce, less likely to remarry, and more likely to be childless. 29 * . Kochhar R: Women make gains in the workplace amid a rising demand for skilled workers. Pew Research Center 2020. https://www.pewresearch.org/social-trends/2020/01/30/womenmake-gains-in-the-workplace-amid-a-rising-demand-for-skilledworkers/; 2020. Employment in US has been expanding in careers requiring greater "social and fundamental skills," and women have been filling these jobs more than have men, contributing to women's career ascendance. As women enter these skilled jobs at a faster rate than men, average hourly earnings of women have grown faster (increase of 45%) than men's (increase of 14%) between 1980 and 2018, helping to close the gender wage gap. 260-287. The authors analyzed Swedish register data of women (n = 641) and men (n = 1246) who ran for parliamentary or mayoral elections. Women were twice as likely to get divorced as women who did not win the elections, whereas there was no association between winning elections and divorce for for men. Likewise, Swedish women (n=105) who were appointed as CEOs had higher rates of divorce rates after appointment, relative to men (n = 715) appointed as CEO. See Box 1 for more details.