Quoting .Sam.:" I wouldn't be able to forgive either way. What's stopping them from doing it again, kwim? "
I feel like they never change, honestly. I know a man that was married for 6 years when he started having an affair. He kept it quiet for awhile, he loved the woman, and then his wife found out. Ever since he begged for forgiveness, they have been working on their relationship and the marriage has been the best it ever has. However, she doesn't know that he's masturbating to another woman, like skyping and smurf- he's been talking to her for months; gets dirty pictures, etc. However, his wife will never know because like he said "their marriage is better than ever."
I know all of this because he's one of my really good friends and has told me. I call him out every now and then, make him feel like smurf... he takes it, and our friendship continues. He knows I'll speak my mind. It's just sad.