I guess don't say nothing. She does seem to be rebelling, there is not much you can say or do, positive or negative it will push her to OM.
You can lay back and break up the affair though. We've all been in this position and it sucks, its demasculating. You know the OM is feeling very manly having his way with YOUR wife. Each time incrimentally helping him out, and hurting you.
The wife see's it as this is what she wants to do.
What to do if this is the situation? The thing that appears to have been working is "bursting the affair".
Getting your wife back at this stage is not going to be easy at all, and you like the rest of us see it happens very quickly.
You can be as loving and dedicated as you want, and they will cheat you. Throw you away.
