Other women.
Even a man who is dating the sexiest woman in the world may occasionally think of someone else during sex: a celebrity like Angelina Jolie or that gal at the local coffeehouse.

It doesn’t mean the guy wants to leave you or cheat on you, but, sometimes, a fella likes variety even when he’s made the choice to be monogamous. Actually, ESPECIALLY if he’s made the choice to be monogamous.

Byron “Big-Naz” Williams, the former bodyguard of raunchy rapper Eminem, as well as the author of a new book, Womanizer: The Uncomfortable Truth About Men and Marriage (Xlibris), puts it this way:

“Even during the best marriage, the sex gets monotonous. So a guy relies on sexual flashbacks where he thinks about his freakiest sex encounters from, say, 10-15 years ago. The key is not to get so caught up in the memory that you shout that other woman’s name, which is why I say ‘Baby’ is the only name you should ever call out during sex.”

Knowing your man might be thinking about someone else during sex can definitely make some women feel insecure. Because of this, their boyfriends try to keep any crushes a secret.

Whatever it takes when they’re not in the mood.
"Sometimes, guys who haven't had sex in awhile will do what we call, ‘Screwing for pride.’” says Mike Hoffman.

"If we do meet a girl who is willing, we'll put our all into it—even if we're not that turned on by her. So, we'll be trying to make up for lost time and lost opportunities and we will try to imagine we're having sex with someone we really wish we were with," says Hoffman.

There may be no way of knowing what the guy you're with is thinking about—but it’s not like women are exactly innocent either. Was that Brad Pitt floating through your mind last night? Yeah, I thought so.