Emotional affairs can be just as devastating as physical ones, and the emotional content of any kind of affair is often the most hurtful part of it. And of course a friendship that is overstepping boundaries is a dangerously slippery slope. Does his wife know how much time/effort he is spending in communicating with your friend? I suspect not.
As you recognise in OP, you cannot stop your friend from having this relationship. But you do not have to discuss it. And if she accuses you of being unsupportive, well it's fine to tell her that no you don't support her in this.
I just want to scream. It's all there, laid out, just waiting to happen. 'his marriage isn't great at the moment, he needs someone to talk to', 'we're just friends who have a lot in common', 'I'm just being a supportive friend'
I don't know why she's annoyed that you don't want to talk about it. I don't know why she expects 'validation' either. Does she bring this friend up a lot in conversation or something? Do you get the idea she's rather obsessed with him?
I was going to suggest that you enquire as to how she would have felt if her husband had been doing this, but that might be a bit close to home if she's been cheated on recently.
Perhaps she is having a moral crisis after finding out? It's not unusual for people who have been cheated on to feel like everybody is cheating, and to reassess what they feel is morally right based on that. She's been hurt, and she is probably both feeling that everyone is doing this, and rejecting that she is anything like her husband, in equal measures.
As for what you do about it: well, you can either tell her that you think that this is an emotional affair, that it's unfair that he is redirecting his attention away from his wife onto her, and that it will be just as devastating as a proper affair should his wife found out, or you can tell her that you don't agree with what she is doing so you don't wish to discuss it.
If she's looking for validation, and you refuse to give it, maybe she'll eventually step away? You can only hope.
She thinks it's for real, that's the problem. She thinks that she has a boyfriend so she's exhibiting all the classic signs of someone bubbling over about their new love. So all this guff about it not being an affair and 'just friends' is obviously delusional.
I think you're going to have to step away, ignore the messages and generally avoid the friend. She already knows you don't approve so there's not a lot of point repeating yourself. Don't get into an arguent because it's pointless. You can't change her behaviour but you can change your reaction and refuse to engage
Maybe you could say, "I wonder if this is how things started with your exH and his OW?" It would be cruel in a way but might clarify what's really happening and why you feel so impatient about it.
Thing is, we all fuck up sometimes and act crazily in one way or another. But our best friends DO gently call us on what we do. It's her delusion and requirement that you support her in this that's the problem for your friendship.
She's obviously in free fall since the break up of her marriage and vulnerable.
Your friend is on a very slippery slope indeed. She may not realise that she's having an affair but she is. I think many women would be more angry at discovering their partner has an emotional connection with another woman than at a physical relationship.
Making 'playlists' is dangerous... a lot of emotional investment and thought goes into those.
You can be her friend but refuse to listen to any talk of this relationship. Be around with tissues later because that part is inevitable.
I absolutely agree with others, an EA is worse IMO than say a drunken one night stand. It is the thought and deceit that goes into it and it is the start of an affair I would imagine.
I was in the process of splitting up with XH and I met someone else, nothing happened between us whislt XH and I were together but I was definitely in love with him before we had even kissed just from emails, texts and talking. XH and I were already discussing a split so it didn't split up our marriage but it most definitely would have done if either of us had done something like that whilst together properly.
I am not sure I could be unsupportive of a friend involved in something like this, in fact my SIL was in a similar situation, I told her what I thought as she asked, I made it clear I thought he was bullshitting her as well as it was the usual 'not happy in marriage' 'we sleep in separate rooms' etc etc. She carried on anyway and we didn't discuss it in detail again, she told me how lovely he was at times, I just didn't really get into conversation about it but didn't say anything negative, she eventually figured it all out in her own time. I did remind her of how she felt when her XH did it to her and all that but she thought she loved him at the time and wasn't ready to listen.
Presumably you know that the wife doesn't know about any of this. Yes? Do you know the wife? Can you threaten to tell her? You don't have to actually tell her. Or not threaten to deliberately tell, just say "you know I am friends with x and you can't expect me to keep secrets for you, it's not fair on me and anyway I am crap at it"
No I understand exactly how you feel. DP fell out in a big way with a friend of hers that was having a full on affair and expecting DP to be thrilled for her when DP was also friends with her husband. It was awful. The friendship ended and I don't think the friend ever understood DPs position.
I also had a friend who did this. He used to use me as a sort of alibi while he was out seeing other men. His bf would call me and say "Hi Cherries, is my bf there?". It was dreadful. We also fell out over it. It's odd isn't it though that none of these people think this is ok if it is being done to them?!
I had a friend who did this, ended up sleeping with the guy behind her hubby's back. She used to use me as an excuse to go into town to meet the other man. It felt horrible and I grew less and less friendly with her. I'd keep your distance for a bit, let her get it out of her system. You have said what you think and nothing you say will change her course if she really wants to do something. I don't see my friend any more, I felt far too guilty about her husband.