Lesbian couples who marry or enter registered partnerships in Finland are more likely to divorce than their gay or heterosexual counterparts, even when accounting for whether they lived together beforehand or had children, according to a new study published in the Journal of Marriage and Family. The researchers found that differences in family formation and relationship history only partly explain why female couples experience a higher risk of divorce. These findings provide evidence that both individual life trajectories and broader social contexts shape the stability of same-sex and different-sex unions in distinct ways.
In recent years, as same-sex marriage has become legally recognized in more countries, researchers have begun to examine how these unions evolve over time. While prior work has consistently found that same-sex couples tend to divorce at higher rates than different-sex couples, less is known about why this is the case—especially among female couples, who show the highest rates of union dissolution.
The authors of the study sought to examine whether certain life experiences—such as how long couples lived together before marriage, whether they had children from previous relationships, or whether they had children together—might help explain the observed disparities in divorce rates. Their approach draws on the life course perspective, which suggests that people’s earlier life experiences influence their later relationship outcomes.
“Prior studies have shown that same-sex couples, especially female couples, have a higher divorce risk than different-sex couples across several countries. However, the explanations for female couples’ higher divorce risk are unclear,” said study author Maria Elina Ponkilainen, a doctoral researcher at the University of Helsinki.
“There is a well-known stereotype of female couples as eager to commit and move in together soon after meeting, suggesting a strong inclination toward serious relationships. Some prior studies have also speculated that short periods of premarital cohabitation, i.e., rapid entry into marriage, could be linked to their higher divorce risk, but no study has tested this assumption. We wanted to address this open question.”
To explore these questions, the researchers used comprehensive administrative data from Finland, covering all same-sex and different-sex couples who entered legal unions between 2003 and 2020. In total, they analyzed data from over 5300 same-sex couples—about two-thirds of whom were female couples—and more than 450,000 different-sex couples.
They examined whether the length of premarital cohabitation, the presence of children from previous relationships, and having children within the current union were associated with divorce risk. They also compared these factors across couple types to determine how much they contributed to divorce patterns.
The researchers found that female couples had a markedly higher divorce risk than other couples. Within ten years, 41 percent of female couples had divorced, compared to 27 percent of male couples and 22 percent of different-sex couples. After adjusting for age, education, and nationality, female couples were still over twice as likely to divorce as different-sex couples, and about 20 percent more likely than male couples.
Premarital cohabitation mattered, but only for same-sex couples. Female and male same-sex couples who had lived together for a longer time before marriage had lower divorce risks. For example, those who had lived together for seven or more years were much less likely to divorce than those who had not lived together beforehand. Among different-sex couples, however, the length of premarital cohabitation was not strongly linked to divorce once other factors were considered.
“We found that female couples entered marriages after shorter periods of premarital cohabitation than male couples or different-sex couples, but its role in explaining their higher divorce risk was smaller than I expected,” Ponkilainen told PsyPost. “It tells us that other factors explain the rest of their higher divorce risk, but I find it likely that these factors are not directly observable in our administrative register data, which do not include information on individuals’ values, attitudes, or subjective experiences, such as relationship quality or commitment to the partnership.”
Children from prior relationships also played a role. Across all couple types, having a child from a previous union was associated with a higher risk of divorce. However, the increase in risk was smaller for same-sex couples, especially female couples, than for different-sex couples. For instance, different-sex couples with a prior child were about 1.6 times more likely to divorce than those without, while the difference among female couples was closer to 1.3 times.
Having children together tended to reduce the divorce risk—but not equally. Both female couples and different-sex couples who had a child together were less likely to divorce than those who did not. However, this protective effect was stronger among different-sex couples.
The researchers had expected the opposite, predicting that shared parenthood might be particularly stabilizing for female couples, who often invest heavily in becoming parents through assisted reproduction. Yet the data indicated that having a child together did not reduce the divorce risk for female couples as much as it did for different-sex couples.
“The findings indicate that we cannot assume that factors that are known to protect union stability in different-sex unions would have the same impact on same-sex unions,” Ponkilainen said. “The findings also highlight the importance of studying within-group differences among same-sex couples, rather than only comparing same-sex couples to different-sex couples as a group, as there are large differences in divorce risk among same-sex couples as well. This is important in order to identify couples who might be at an increased risk of divorce and who could benefit from external support during their partnership, as well as in coping with the possible short- and long-term negative consequences of divorce.”
Adjusting for all three factors—cohabitation length, prior children, and shared children—narrowed the gap in divorce risk between couple types, but only modestly. These variables explained about one-fifth of the difference in divorce risk between female couples and different-sex couples. They accounted for roughly one-third of the difference between female and male same-sex couples. Even after accounting for these variables, female couples remained the most likely to divorce.
“The findings indicate that the risk of divorce is shaped by a complex interplay of various factors, which include both previous relationship experiences and current union characteristics,” Ponkilainen explained. “This emphasizes how individual life trajectories contribute to the resilience and vulnerability of each union over time, and how these life trajectories may differ for female couples, male couples, and different-sex couples due to different legislative and normative contexts surrounding these unions.”
While the study makes use of rich, population-level data, it also has some limitations. The researchers note that the Finnish data system does not include measures of gender identity or sexual orientation. This means that same-sex couples were identified based on legal sex, not self-reported identities.
Additionally, the study could not capture information about the quality of relationships, the reasons for union formation, or emotional commitment. These factors may vary across couple types and influence the decision to marry or stay married.
Finally, the findings are based on the Finnish context, where same-sex couples have had access to legal unions since 2002 and to marriage since 2017. The country also has relatively liberal family laws and a high degree of social acceptance of nontraditional family forms.
“The results are based on the Finnish context, and I would be cautious about generalizing them to other countries,” Ponkilainen noted. “The legal and normative context in each country affects same-sex couples’ opportunities to enter marriage and have children, and it may also impact their union stability and risk of divorce.”
Regarding the next steps for this line of research, Ponkilainen said that she “would be interested in further exploring the explanations for the higher divorce risk among female couples. In particular, I am curious about factors that influence who enters marriage, as well as potential differences in the degree of commitment to the partnership among couples who choose to marry. At the same time, there are several other unexplored factors to consider, as the field of study is still evolving.”
The study, “Same-Sex and Different-Sex Couples’ Divorce Risks: The Role of Cohabitation and Childbearing,” was authored by Maria Ponkilainen, Elina Einiö, Mine Kühn, and Mikko Myrskylä.
