Most adult men (more on that later) cheat because they feel (rightly or wrongly) some need is unmet in the relationship with their partner. It doesn't matter if they're even aware of their unmet need. The majority of these men do not (initially) become involved with another woman for the sex - they like getting the attention, respect, appreciation, or simple good conversation and companionshipnthey don't get from their partners. For THESE men, you really CAN keep them from straying by keeping them satisfied at home.

Some men cheat because they are natural born hound dogs and can't seem to help themselves with the obsession. They would stray no matter how good they have things at home. They are (fortunately) rather rare, and could probably be classified as being mentally ill.

Other "men" cheat because they never grew up, and are immature boys no matter what their calendar age may be. They are also usually immature in many aspects of their lives. They are (unfortunately) not all that rare.

Finally, there are the men who have matured, but have developed an arrogance and sense that they are entitled to do what they do. They are narcissists. If your cheater is a powerful and successful man who's used to being the alpha male and the center of his world, he may well be in this category. Fortunately, there are plenty of powerful and successful men who are good and faithful, but the temptation IS there for those whose egos have grown too large.

If your man cheated because he was seeking to fulfill some need not being met in your relationship, fulfilling that need will prevent his urge to stray. It may be a "need" that you are unable or unwilling to meet, but if you do, he'll stay at home

If your man is a hound dog, he can't be changed - it's in his very nature.

If your man is an immature boy in a man's body, growing up can cure him of this and make him settle down - but getting him to grow up will not be an easy task.

If your man is a powerful narcissist, he can change but he doesn't WANT to. Unless you can elevate yourself to his level of power, you will not be viewed as a partner, but as a tool or accessory to be used.

My advice is that unless there is some overriding reason (such as having children with this man) to try to save your relationship a man in one of the latter three categories of cheater, don't waste your time when there are so many good men out there who don't require the extra effort.

There are a lot of reasons men cheat -- even happily married men. It's a myth that men cheat because they aren't getting enough at home.

They do it to make themselves feel good. Some men can be monogamous and some cannot. It's about 50-50%.

But does it really matter? A man who cheats on your while you're dating will cheat on you for the rest of your life.

Do you really want that? You cannot fix him or change him.

It is important to note that it has really NOTHING to do with you. It certainly has nothing to do with anything you are lacking. Only one factor that has to do with why a boyfriend cheats on his girlfriend is that she doesn't become his exgirlfriend immediately.

The other reasons are completely HIS faults. So, like Tanstaaf says, when you are ready to find a man mature enough to warrant someone like you, you will move on. And you will be happy. We each learn from each of these incidents, so don't beat yourself up. It happens to the best of us. The important thing is to recognize whether or not he is the type to cheat or it was a one-time thing. Trust your gut here. If he is the type to cheat, move on. Give yourself time to grieve. Take some time to learn about yourself, about your instinct, about the kind of man you are looking for, and then go back out there and find a better man. He is out there looking for a woman who won't cheat too!