Oh boy. We're not looking to open up some age-old battle of the sexes here, but we will say one thing: the old clichés really are true. Women look for commitment, and men couldn't run away faster if their balls were on fire. We're big kids at heart, us men, and the idea of just playing with one toy for the rest of our lives just doesn't seem right - especially when there's an infinitely big Lego set out there.
That being said, there are some men who are more than happy to settle down and say those magic words. If you're one of those, and your partner is being unfaithful, you're going to find that the tables are turned. Cheating women have no interest in the long-term anymore, and clearly they don't see a future with you. If she can't or won't talk about commitment, then there's something clearly wrong.