"Okay, it can be kind of a pain sometimes," says Cal, who has never had a relationship not end with her girlfriend discovering that he's been cheating on her, "but it's worth it."

For guys who don't suck as bad at being a boyfriend as they do at almost everything else, anyway. And there's always a part where it really is fun.

(Someday, Cal will come across the concept of polyamory. He'll feel a lot less defective after that.)