Conflict, infidelity, and lack of intimacy are some of the top causes of divorce. But new data compiled by Divorce.com, shared with Fortune ahead of its publication on the website, shows another factor: a woman being the main breadwinner.

Regardless of whether the household has one or two incomes, a female main earner in a heterosexual marriage is associated with a divorce rate that is three times higher (31 vs. 11 per 1,000) than marriages with a man who earns more.

Further, in single-income homes with female breadwinners, the divorce rate is twice as high (54 vs. 20 per 1,000).

Female breadwinners, the findings continue, represent just 16% of all households—but account for 42% of divorces, “highlighting a significant imbalance.”

The data is based on the 212,000 respondents of the Census’s American Community Survey from between 2012 and 2023, all of whom had filed for divorce at the time of the survey. It was collected from all 50 states, included respondents from 18 to 99, and reflected U.S. income distribution, with 75% reporting income below $100,000 ad 11% reporting incomes above $150,000.

The pattern appears to have held for over a decade, as data from 2013 shows female earners accounting for 41% of divorcing households while only making up 17% of all U.S. households.

That’s when University of Chicago professor of economics Marianne Bertrand co-wrote a working paper exploring the topic. She saw the divorce-rate gap as a grim societal reality, as a woman outearning her husband was found to cause unhappiness in a relationship, she found, and even “doom” the marriage.

“The notion that a man should earn more than his wife not only impacts marriage rates, the researchers show, but also influences how much a married woman works outside the home and how household chores are divided,” a press release on the research noted. “Moreover, women who deviate from that norm pay a social price.”

Divorce.com CEO and founder Liz Pharo, though, believes that such a divorce gap could be evidence of empowerment.

“In previous generations, success for women was usually measured by marriage and family stability, but today, career achievements and personal fulfillment outside of traditional roles are more central,” Pharo tells Fortune. “Women are no longer financially dependent on their partners, which means they’re more willing to leave unsatisfied marriages instead of staying out of necessity.”

The finding is not even uniquely American, as a 2024 data analysis of couples in France found that, all other things being equal, “couples in which the woman’s share of the couple’s total income is higher than 55% are significantly more unstable than other couples. They are from 11 to 40% more at risk of union dissolution than equal-income couples, and the risk of union dissolution increases with the woman’s share of couple’s total income.”

In the U.S., the share of married women who were earning at least as much as their husbands had more than tripled in the past five decades as of 2023, Pew Research found. Husbands, it discovered, were the breadwinners in 55% of marriages, while 29% of couples were earning about the same and 16% earned more than their spouse.

“Women are gaining economic influence within their marriages,” Carolina Aragão, a Pew research associate and author on that research, told Fortune at the time.

But despite sometimes earning more than their husbands, Pew found, married women spent more of their downtime on childcare and household chores than the men, with one exception: when the woman was the sole breadwinner.

That imbalance could also play a role.

“Modern women have higher expectations for emotional and personal fulfillment in relationships, leading to a lower tolerance for unhealthy or imbalanced partnerships,” says Pharo. “Divorce isn’t as stigmatized as it once was. Women, especially those who are financially independent, feel more empowered to walk away from marriages that don’t serve their emotional wellbeing.”