"Whenever one partner is working outside the home, he or she has more opportunities to meet other interesting people that may represent excitement and exploration outside of home life," she says.

Logan Levkoff, sexologist and author of "How to Get Your Wife to Have Sex With You," adds: "Our perceptions of stay-at-home dads vary based upon our understanding or acceptance of traditional gender roles. As more women enter the work force (and feel fulfilled by our out-of-home jobs), we like partners who are willing to pick up the slack. That being said, it is a double-edged sword. Sadly, if a man feels emasculated by his SAH status, it is very difficult to have a fulfilling sex life."

In the end, though, parenting is about a lot more than just who, if anybody, stays home with the children.

"The role of a 'dad' is changing, both in straight and gay relationships," says Bucatinsky. "People look for partners now with far more complex and varied qualities rather than just one."

Raykeil agrees. "I think we're in the course of redefining masculinity and fatherhood and 'providing,' " she says. "After all, what better way to provide for your family than providing a loving and engaging relationship with your kids?"

And that, everyone can agree, is sexy.