A fair number of my male friends discuss their sex lives with me, and I with them. It's often useful to get different perspectives on things and truly isn't a big deal in isolation.
Its not in isolation, in this situation, though.
This knee jerk, heterosexual strict monogamy, sex = guilt, mindset is just so destructive
Except the OP and the OM have both promised strict monogamy. If that's not what they want.....they need to speak to their respective spouses. Not deceive them.
That's where the guilt comes from. Not from sex. But from him hiding the extent of the friendship and the OP, hoping he does fancy her leaves his wife for her.
In a full blown affair, the sex is probably the least damaging part for a lot of people. Its the months of lies, that's the biggest thing to get over for a lot of people.
So no. Sex doesnt = guilt. Lying to your partner = guilt. As it should.
Discussingher sex life with someone else is not the same asdoingthe deed with someone else - and, even if she was, if she made her partner aware and he's happy with the situation (and I've been there done that and we're still married several years later) and the other woman is ditto ditto ditto - what's the problem?
If they did that. There would be no problem. But they havent. OP wants to know his feelings, ending the friendship is not an option for her. The only positive outcome of this, in her own words, are that he wants her and leaves his wife.
The OP doesnt want an open relationship. She wants him to fancy her and leave his wife. That's not an open relationship.