Would he be rejecting his gf by having either he or she decide that she didn't need to force herself into a new family dynamic that is resistant to her? I don't agree with that....it seems more in-your-face, accept-me-and-all-I-come-with-or-to-hell-with-you/I-did-nothing-wrong-or-immoral of an attitude. His parents didn't turn around from the visit because he was there. They just are unwilling to accept the relationship he chose. Would it be better for them to welcome her into the family with open arms? Pretend that the past didn't happen when they were witness to it, as the sibs seem to have done - a 20-year relationship erased, a family member replaced? Or, go to the event and refuse to acknowledge that she is in the room at all? "Just have a nice visit," like great-grandma has suggested, when instead she is left with her stomach tied in knots with the elephant in the room?
Anyway, it has nothing to do with me, anymore - it is just an observation. My IC pointed out that his ability to do what he did does seem to be rooted in his larger family dynamics.
As far as the example set for my kids - I sincerely hope that I am raising them to internalize that cheating is wrong; not an option. There is no grey area there. Do I believe that a marriage has a chance to survive it if it happens? Yes, if both parties are willing to do the work. But it is very messed up that people think that this is an option to begin with, when it causes so much destruction and pain.
What I've talked about with my son in the past: people are human, and fallible. My parents both smoked; my mother was an alcoholic. It didn't stop me from loving them, but I certainly didn't want to emulate those behaviors, either! Of course he loves his dad, but I hope that he would never think that cheating is ok. Forgiving a person doesn't mean that you forget, or wipe the slate clean and make everything ethical and nice-nice - wrong is wrong.
ANYway, I am taking D down to LI to the ocean beach and staying over at college friend's. I went for my recheck of my ear, and the hearing is slowly coming back (my eardrum burst when I was on vacation - ouch!) Glad it is summer!