By Laura Snyder

Yeah, yeah, yeah, blame it on evolutionary wiring. But there's more than just a genetic predisposition to infidelity. Guys have all sorts of reasons for getting some on the side. Read on, ladies, but you're not going to like what you hear...

He's Unsatisfied

It could be about the sex - he's not getting enough, or it's not hot enough - or the relationship itself. But whatever's missing from the mix, he thinks it's a lot easier to fill that void with an affair than it is to fix what's not working.

He's Retaliating

Ah, revenge. Plenty of men think that the only way to "even the score" against a girl who's gotten some on the sly is to do the same. Easy prevention - just don't give him reason to seek revenge. Just watch out for the guy who cheats to get back at all the women in his past who've done him wrong.

He Loves the Chase

Some men just have trouble giving up that thrill of the hunt they got in their single days. Or maybe he's nostalgic for the variety of vixens he could choose from before he settled on just one. Often, this cheater is motivated by the thrilling possibility of getting caught. He's the kind you find hooking up with your sister or your best friend. In your bed.

His Ego Needs a Boost

Nothing lifts the self-esteem like knowing you're still appreciated by and attractive to the opposite sex. Some (insecure) men need the validation of self-worth that cheating can provide. Infidelity in this case is often more about the cheater than it is about the person being cheated on.

Because He Could

The opportunity came up and he just couldn't say no. Sadly enough, some men are tempted to stray just knowing that no one will find out and no one will get hurt. As someone once put it, "Women need a reason to cheat; men just need a place."