Women are more likely than men to initiate divorces, but women and men are just as likely to end non-marital relationships, according to a new study that will be presented at the 110th Annual Meeting of the American Sociological Association (ASA).

"The breakups of non-marital heterosexual relationships in the U.S. are quite gender neutral and fairly egalitarian," said study author Michael Rosenfeld, an associate professor of sociology at Stanford University. "This was a surprise because the only prior research that had been done on who wanted the breakup was research on marital divorces."

Rosenfeld's analysis relies on data from the 2009-2015 waves of the nationally representative How Couples Meet and Stay Together survey. He considers 2,262 adults, ages 19 to 94, who had opposite sex partners in 2009. By 2015, 371 of these people had broken up or gotten divorced.

As part of his analysis, Rosenfeld found that women initiated 69 percent of all divorces, compared to 31 percent for men. In contrast, there was not a statistically significant difference between the percentage of breakups initiated by unmarried women and men, regardless of whether they had been cohabitating with their partners.

Social scientists have previously argued that women initiate most divorces because they are more sensitive to relationship difficulties. Rosenfeld argues that were this true, women would initiate the breakup of both marriages and non-marital relationships at equal rates.

"Women seem to have a predominant role in initiating divorces in the U.S. as far back as there is data from a variety of sources, back to the 1940s," Rosenfeld said. "I assumed, and I think other scholars assumed, that women's role in breakups was an essential attribute of heterosexual relationships, but it turns out that women's role in initiating breakups is unique to heterosexual marriage."

Perhaps women were more likely to initiate divorces because, as Rosenfeld found, married women reported lower levels of relationship quality than married men. In contrast, women and men in non-marital relationships reported equal levels of relationship quality.

Rosenfeld said his results support the feminist assertion that some women experience heterosexual marriage as oppressive or uncomfortable.

"I think that marriage as an institution has been a little bit slow to catch up with expectations for gender equality," Rosenfeld said. "Wives still take their husbands' surnames, and are sometimes pressured to do so. Husbands still expect their wives to do the bulk of the housework and the bulk of the childcare. On the other hand, I think that non-marital relationships lack the historical baggage and expectations of marriage, which makes the non-marital relationships more flexible and therefore more adaptable to modern expectations, including women's expectations for more gender equality."