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As American wives increasingly outearn their husbands, many couples experience what relationship coach Suzanne Venker calls “role-reversal stress.” This stress can be deleterious for their emotional and sexual lives, three studies published in the American Sociological Review suggest:

• Harvard sociologist Alexandra Killewald found that if a husband is employed full-time, the couple has a 2.5% chance of splitting up in the next year; if he isn’t, the likelihood of divorce rises to 3.3%.

• Christin Munsch of the University of Connecticut found that husbands who are economically dependent on their wives have a greater propensity to be unfaithful.

• Three sociologists from the Juan March Institute and the University of Washington found that the frequency of marital sex is lower for couples in which the husband often does traditionally feminine chores such as cooking, cleaning and taking care of kids, and higher if he does masculine ones like yard work, paying bills and car maintenance. Julie Brines told reporters that she and her co-authors were surprised at “how robust the connection was between a traditional division of housework and sexual frequency.”

It seems younger generations are taking note. A University of Texas survey in 2014 found that younger millennial men, then 18 to 25, were likelier to agree with the statement “it is much better for everyone involved if the man is the achiever outside the home and the woman takes care of the home and family” than Generation X men or older millennials had been at the same age.

These evolving attitudes may reflect differences in the households in which these young people grew up. In 1987 wives outearned men in less than 25% of households. By 2015 that share was 38%.

How should society understand and address role-reversal stress? It’s neither possible nor desirable to revert to a world in which women lack choices and men don’t respect women’s accomplishments and ambition. For the best outcome we must openly discuss the benefits and risks of emasculating men while empowering women and find a harmonious balance. The most successful couples I have treated are the ones in which the spouses aren’t afraid of embracing both the differences between and the equality of the sexes. It’s crucial for couples to respect each other’s unique abilities and pay attention to the power balance in the marriage.

Romantic attachment and sexual desire are rooted not only in culture but also in biology and evolution. There is an inverse relationship between oxytocin and testosterone. That means the more nurturing a man is with his children, the lower his testosterone.

Men need to be men, and women shouldn’t fear taking on traditional nurturing roles, which needn’t threaten their careers. The best marriages are those in which couples are honest about their feelings rather than prone to make assumptions and learn they’re mistaken after it’s too late.

It’s a moral victory that women now have the opportunity to be breadwinners, but this cultural progress comes with psychological distress that is worth understanding for the benefit of men, women and children.

Ms. Komisar is a New York psychoanalyst and author of “Chicken Little the Sky Isn’t Falling: Raising Resilient Adolescents in the New Age of Anxiety.”