Question: how did you actually feel while the people were discussing their views on the infedilities of their partners and the consequences of that for them. I hear from what you say that you worked through your cognitive raison d'etre.
My question lies purely in my deeper curiosity about the life you live and the mixture of roles that you have and how all this sits with your deeper and broader range of feelings.
We all want more when we have less, it is the nature of the beast. It also maintains heightened interest. You may find that if you did have lots more time to be leisurely together, you might just be that - leisurely with less excitement in your lives. At this point in your lives, what you have is likely to be what you want.
My friends have moved on, and were not discussing infidelities from raw place, but did point out longterm effects on trust. One ex was was serial philanderer and I don't know details of other one - Just he did it, she knew and he was out. Such discussions make me uncomfortable, because I try not to deceive myself.
When I fell for lover I ended a longterm relationship because it became dishonest before I was technically unfaithful. As we were not living together although spending all our nights together it was not complex from practical perspective. I felt like a total cow for no longer loving a good bloke who'd done no wrong though. my lover has been married for thirty years and I didn't want responsibility of end of marriage if 'we' came to nothing, so began affair in deceit of his wife. He confessed and tried to leave, but couldn't in the end. he finished with me and did his best to be faithful, but became depressed. I missed having him in my life, because we were so attuned. It seemed mad for him to be doing the right thing and both of us missing each other and unhappy.
I hate it when the unfaithful claim that it is better for deceived partner(s) because deceiver(s) can be more generous/thoughtful/happy in relationship when getting needs met elsewhere, but sometimes there is truth in it. Their marriage trundles along better when he is not depressed and missing me. Not a justification for infidelity, but seems to be a fact as far as I can tell.
I am living my life short of my own ethical code, but do not feel actively guilty most of the time. I do not consider the marriage to be healthy for reasons I wouldn't discuss here, but know that's merely my opinion. I think she has rights within her marriage and right to dignity, but obviously I don't value these rights enough not to be a co-respondent. And of course if marriage was sounder he would not be doing what he's doing. Being tempted by available sex in longterm relationship is understandable, but this is rather more than that.