Once upon a time, the majority of family incomes in the U.S. followed a predictable pattern: The husband was the primary breadwinner, and the wife was largely responsible for managing the household and children. But, while that’s still the reality for some families, it’s not for many others. More than a third of wives now earn more than their husbands—and new research suggests it’s stressing men out.

The study, which was published in the Personality and Social Psychology Bulletin, analyzed more than 6,000 American heterosexual couples over 15 years. Researchers found that husbands were anxious when they were the only breadwinner in the family, but that their stress levels went down as their wives made up to 40 percent of the household income. After that point, though, the husbands’ stress levels gradually increased. The stress levels of men were highest when they were entirely financially dependent on their wives. The only situations where this wasn’t the case was when the wives outearned their husbands at the beginning of their marriage.

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What’s going on here?

A lot of it comes down to societal expectations, says clinical psychologist John Mayer, Ph.D., author of Family Fit: Find Your Balance in Life. “As much as we would love to think that we’ve changed our mindset on stereotypical gender roles, we are actually still in the generation of attachment to the primitive concept that a woman’s place is in the home and the man is the breadwinner. We’ve come a long way, but there is still work to be done.”

Gail Saltz, M.D., a psychiatrist and author of The Power of Different, agrees. “Cultural norms die hard,” she says. “For a lot of men—even men who don’t want to feel that way and are progressive—it can feel like they’re being outdone in some way when their wives make more than they do.”

While societal expectations likely play a role, it may also be that husbands are becoming more stressed because they’re taking on more household roles as their wives earn more, says Lauren Smith Brody, author of The Fifth Trimester: The Working Mom’s Guide to Style, Sanity, and Big Success After Baby. “What I suspect is actually going on is that, as mothers’ income starts approaching that 50 percent of the household income mark, families are becoming more equitable in their distribution of housework and child care,” she explains. “Meaning, dad is taking on more at home in addition to his job—or, at least he feels like he should. Which, as every working mom who’s ever done a load of laundry at 11 p.m., or sat in a meeting and tried to visualize the amount of milk left in the fridge, knows is stressful.”

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More equal earnings between husband and wives may also change the dynamics at home and the expectations women have of men, says Katherine Goldstein, creator and host of The Double Shift podcast. “Women often shoulder more childcare and housework, even when both members of the couple work full time,” she says. “Are men stressed because they aren’t the breadwinner, or are they stressed because women’s economic power is putting more pressure on them to contribute to the household in other ways?”

At the same time, women likely want more control over major decisions as they’re making more money. Men may struggle with being asked to give up more of their share of power, whether it’s perceived or otherwise.

The main challenge women face in this situation is “still too often being expected by her husband and society to be responsible for the mental load and shoulder more household and childcare tasks, on top of her breadwinning job,” Goldstein says.

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So, what should families do about it?

Clearly women shouldn’t apologize for earning more, and it’s important for women to remind themselves of that fact, Saltz says. But, at the same time, this stress should be addressed. “He might not even realize he’s not feeling good about himself but might be more irritable, snappish, or sensitive about certain things,” she says. “It doesn’t mean he’s prehistoric or doesn’t want good things for you, but he might be having trouble with his own insecurities.”

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Creating a culture at home where you tell your partner that you’re proud of what he’s doing, along with applauding the contributions he makes to the family, can go a long way toward helping, she says. (The hope is that he’ll do the same for you, too.)

It’s also often a good idea to take a step back and rethink how you’re treating your household. “Stress happens because we do not treat our home like our most important organization,” says organizational management specialist Eve Rodsky, author of Fair Play. “When things are done on the fly in how we make decisions in the home, and we just think we’re going to figure it out, bad things happen.”

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That’s why Rodsky recommends setting expectations for what each member of the household is responsible for, and communicating as things change. “When you start having these conversations early, preferably before children, people are more willing to have these conversations when they need to,” she says.

If you’re already past that point in your marriage, it’s OK. Brody just recommends having an honest conversation with your partner about how you do and don’t feel supported by society and your workplace as working parents. Then, she says, “push as a team to make those corrections and model equity in the home for our next generation.”

Next up, does career success for women have to mean loneliness? Founders Carolyn Childers and Lindsay Kaplan of Chief say absolutely not!