I agree with you that is/was a major red flag for me. His wife is very concerned about that because he has never really had a low sex drive. Can a man be so wrapped up in an EA that it affects his feelings for his wife sexually?
Funny the last time we talked about "us" with my wife. I brought up the fact about her and OM still talking (I know not the right thing to do) about her EA and called it an affair. She laughed and said how can you call this friendship an affair.
My thoughts are that they are both still so caught up in something that they really don't want to be in. That they had this connection that they will never have with their spouses. You know the story. Anyway OM has talked to a lawyer and was not wearing his wedding ring for awhile.
My wife told me she was proud that when she talks with him that she no longer has the same feelings for him that she did before. That I should back off and trust her even though she has told me she felt that connection with him, which I have backed way off.
Our counseler who is seeing us both as indvs told me that OM is the whole reason right now that we are having problems. She has told her a couple of times that she needs to stop talking to OM. I asked her what I should be doing different and she said nothing. Just keep being the best person and husband that you can be. Who knows where this thing leads. I am sure as you where she is struggling with her feelings. As you say the sex thing with him does have me worried.