Men Lie, Women Lie

Why do men cheat? Excuse me, correction, why do people cheat? After sitting down and thinking long an hard about that question, the only reason I could come up with was selfishness.

Only a selfish person would put their own wants in front of their partners feelings. Only a selfish person would go out, and seek pleasure (or companionship, or whatever they're looking for) without thinking twice about the outcome of the situation.

I feel that rather than just cheating on someone, you should decide whether you can do without that person. If you can't, then DON'T DO IT. And if you can, at least have the decency to end the relationship before you end up hurting the person beyond repair.

But I forgot, they're selfish, so they will want their cake and eat it, too.

And after the truth comes to light (and the truth ALWAYS comes to light) they constantly lie. I feel that if you are bold enough to step out, then be man (or woman) enough to admit to it.

If you didn't put the pieces together yet, I've been in this situation before. Someone else came to me with the same situation as well and it just pissed me off to know that someone can be faithful for almost 4 years and the next person can't. But I see it as a lesson learned.
I'm just venting right now, but what do you guys think about liars and cheaters?