"More housework, less sex for married men: study"?

I would appreciate some theory for this finding.  I think that there is a real endogeniety problem here.  Something else is different in those households where men do more housework.

His study, "Egalitarianism, Housework, and Sexual Frequency in Marriage," looks at straight married couples in the United States, and was based on data from the National Survey of Families and Households.
The study was co-authored by University of Washington sociologist Julie Brines and doctoral candidate Katrina Leupp.
Men in the study reported having had sex an average of 5.2 times in the month prior to the survey, while women reported 5.6.
But both men and women in couples with more traditional household labor divisions said they had more sex. . . .