Increasing career opportunities for women mean that nearly 25% of wives now earn more than their husbands.

If you’re not careful, this can add further strain to the delicate balancing act of marriage.

“The man should admit defeat in a humorous way saying, ‘Honey, it’s not fair. They pay you for your brains and your beauty. That leaves me to fight with one hand tied behind my back,’” says Dr. John Hoover, a Minyanville professor, executive coach at Partners In Human Resources International and author of How To Live With an Idiot: Clueless Creatures and the Women Who Love Them. “To be a player in the household economy, given the husband’s diminished cash flow, he might need to pick up more househusband responsibilities.”

The Bureau of Labor Statistics reports that 8.1 million women, or 24.1% of women in the labor force, earned more than their working husbands in 2001. In the bottom 20% of wage earners, 18.3% of women earned more than their spouse; in the top 20%, only 0.4% of women earned more. In some families, researchers found the wife is likely to exert more control over financial decisions, which often means more money is spent on the children.

This isn’t surprising and reflects what sociologists call “positive assertive mating” - a fancy term for an obvious fact: smart, well-educated women with solid earnings potential tend to marry smart, well-educated men with excellent career prospects. Another explanation for the narrowing income gap at the top: many women put their careers on hold for motherhood, especially when the kids are young. The wife then falls behind her husband on the career track, which results in lower pay - no matter how high-powered her job may be.

But the overall trend is clear: “Dual-earner couples are swiftly replacing the traditional married couple model of a ‘breadwinner’ husband and a ‘home-maker’ wife,” Anne E. Winkler says in a report for the U.S. Bureau of Labor Statistics. “From 1970 to 1993, the proportion of dual-earner couples increased from 39% to 61% of all married couples.”

So how do you keep the income gap from becoming a black hole that swallows your marriage?