My best friend found out last year that her partner of five years, the father of her two children, had been cheating on her for seventeen months. He was cheating on her when they moved into their first home. He was cheating on her before, during, and after her second pregnancy. He left the night she gave birth, purportedly to go home to get some rest/change, and she later found out he was with his mistress. It was despicable and devastating. He was raised in a really rough home, by a drug-addict father who cheated on his mother and brought prostitutes in the home.

Almost exactly a year later, he's a different man. He's a loving and doting father. He is extremely forthcoming about what he's doing, who he's with. He cut the friends who encouraged his cheating out of his life. He is more loving, respectful, and open with my friend than he ever was, even before the cheating. I never could have anticipated that I would stop hating him after finding out what he did, but he has convinced me a thousand times over that he has grown from that person and that he is a far better man now. Their relationship is much better for having gone through it; while it was extremely painful, my friend is a better wife and mother for having experienced it. She communicates her feelings, her fears, and her troubles easier. She is more loving and nurturing. She is stronger and more capable.

So what I'm saying is that after that experience, I would say that it's absolutely possible that he can change. He has to want to, though.