MEN: Why get married if you're going to get "bored" with your wives?

Not all men, but I hear enough stories of "my wife his great, however, I'm in love with Becky." Why not just stay single if you're going to get bored after a few years? And why not work hard to re-ignite the flame?? I don't get the logic in allowing yourself to give up so easy. Why get married?