I was listening recently to an interview with a marriage counselor who is considered very prominent and successful. She said that the problem with this sort of situation is that the wife may forgive her husband, but she cannot forget all the mistresses and is so grossed out that she has a hard time happily having sex with her husband. The essential trust and love that really lets a wife let go in the bedroom is gone for good, and the mistress is (metaphorically speaking) always in bed with the couple, always a presence to which the couple compares her sexual performance. The lack of sexual cooperation on the part of the wife is what usually leads to divorce a few years after the affair, even if all is forgiven and the husband remains faithful.
Forgive, but never forget-—right?