Want a happier marriage? Share the housework equally.

When Facebook founder Mark Zuckerberg announced he would take two months of family leave following the birth of his daughter, he earned praise for fighting the "stigma" that still surrounds men who take family leave.

"Studies show that when working parents take time to be with their newborns, outcomes are better for the children and families," Zuckerberg writes in the announcement. New research also shows that men in families where both parents work, like Zuckerberg's, can strengthen their marriage by doing something very simple: splitting housework and child care equitably.

When women first entered the workforce in large numbers in the 1970s, says demographer Frances Goldscheider, that put a lot of stress on the family. Women were still expected to do the lion's share of the work of running a household, a phenomenon Goldscheider and other researchers call "the second shift."

Women had dipped their toes into the male-dominated world of work, but no one, Goldscheider says, was talking about men taking on a greater share of the traditionally feminine work of keeping a house and taking care of children.

Although it's difficult to draw a direct causal link, researcher Stephanie Coontz says the divorced women and men she had interviewed for her research said that conflict over housework and child care was a factor in their decision to split up.

"In many cases, conflict over how the men adjusted — or, often, failed to adjust — was a very common factor," Coontz says.

If women working was once a threat to marital stability, however, things appear to be changing.

Goldscheider has authored a roundup of the latest research that shows how changing attitudes about masculinity and greater involvement in housekeeping and child care among men actually helps strengthen marriages. Men doing more chores can help protect against divorce. The more time men spend with their children, the more satisfied both partners say they are with the relationship.

Men who want to protect their romantic relationships from the stress of the "second shift" should follow the advice of Zuckerberg's colleague, Facebook COO Sheryl Sandberg, and "lean in" at home.