My take is that communication gets better, which in turn makes the marriage better on that level, the WW don’t have the same feelings as how the sexual aspect of what they did tarnishes the marriage. To them the affair worked like a charm to make the marriage better for them, while the BS suffers, mostly in silence, while having visions of their WW having sex with their AP. For the men they want to keep the marriage, so it’s not worth it for them to open the can of worms. They don’t want to send their WW back into a shame cycle, so they just swallow the sandwich.
First off, this isn't just about the BH/WW dynamic. Women can have just as much trouble getting over the sexual aspects of adultery, and men can find just as much comfort in the return of good communications. If it were as generalized as this, it would be better for WW's to file for divorce and never bother to explore the possibility of R, because what you're saying is that men can't heal. Which leads me to my second point...
Healing isn't about anything the WS is doing. Certainly, in R they need to have made the changes necessary to be a solid partner again, but other than that, healing is in the hands of the BS. There is NOTHING a WS can do which will MAKE a BS heal... particularly if they don't want to. Many times, we hold on to our pain, as if it had some intrinsic value. It's almost like if we were to release it, the offense against us wouldn't matter; WE wouldn't matter. Maybe we would be in danger of it happening again. Maybe the WS would "get away with it". Maybe we've "settled" for something tarnished and dented and can no longer take satisfaction in it being "ours" (a misguided attempt at "ownership"). Whatever. There are lots of reasons to hold our injury close and refuse to release it. But we don't heal UNTIL we release it.
I took an accountant's view of it, even though I'm not an accountant. I checked my balance sheet, realized that there's no way my WH could EVER pay me back for the pain he'd caused, and wrote off his "debt". This wasn't at the beginning, of course. This was after I felt he'd done everything he was capable of to become a safe partner, because that's ALL he can do. He doesn't have a time machine. And I can never be completely sure of him, but it didn't matter that I was completely sure of him before. It turns out, the only one I need to be absolutely sure about.. is ME. I'm stronger than I was, less dependent, more confidant in my ability to be on my own if needs be. I've dealt with the last vestiges of my innate fear of abandonment. I'm not going to get splattered again, bug meets windshield. I'm enough now.
A sense of honor has always been important to me. If I say I'm going to do something, I do it. I said I would try for R, so to hold onto a grudge, past the point where everything possible had been done to remediate its cause, would have clashed with what I view to be My Word. That's not to say I never have pain, only that I don't hold onto it. I don't indulge it. I don't cleave to it. If I get a trigger, I notice it and I allow it to pass. At this point, it's just the ghost of a thing that once happened. It has nothing to do with who I am TODAY.
Who I am today stands by her choices. My WH didn't MAKE me choose R. I chose it for myself and I will treat that choice honorably, not holding back and not nursing a grudge. I haven't been tied up and tossed in the trunk of his car. I'm the driver of MY life. I may have been victimized, but I'm no longer a victim. I am free to change my direction at any time, so long as my sense of honor is vindicated by that choice. So, if I choose to leave, it's not going to be because my fWH cheated five years ago. It's going to be because we can't find even footing in the now.
We don't have to choose to keep a cheater. We just don't. The daily trappings of life might make it harder for some than others to break free, and it might take longer to organize an exit, but no one is truly trapped. I think if we do choose to stay, it's incumbent upon us to do our work, get our healing accomplished, and be as good as our word.