Hi Sue,
I believe Andy's comment is that your H is rebelling to prove opposite sex friendships are acceptable on a platonic level. Then your protests about the OW put you in the position of being apart of what he is rebelling against, so you are part of the problem. On the other hand, if you show your support for his friendship to her, then you are part of the solution or in other words, you are showing him you are on his side in his stance instead of against him.
However, there is still the issue of consideration for your partner. But instead of confronting him about it which may push him futher away, consider a true 180 in every sense and plan a late night out for yourself when you know he will be home. Be mysterious and tell as little as possible about your plans. Ideally, cross paths as he comes home, be heading out and try to get out with only a "Gotta go..." This way you place him in a position of experiencing your point of view and he just may relate it to what he has been doing. Oh BTW, if you do go out, do plan something that you will enjoy spending the time to do and not just to be out to make the point. It is as much for your benefit and it is for his, hence a 180 in many different ways.
P.S. Due to computer issues here, I see Andy responded before I got my post up ... oh, well.
