I also think it's more than just one bad moral choice or whatever. I think people that would consider leaving a married partner for what they perceive as a better option have more wrong with them than just making one bad moral choice. I've just seen so many accounts of dysfunctional OP's and WAS here on the boards; I think it is more than just that.
Karen,
Sometimes the WAS is in the fog of a new romance. Sometimes they behave clearly on "script".
However, the choice to have the affair was a moral one.
Sometimes we talk about MLC and the "fog" as a way of increasing our hope that they'll snap out of it. I think new romances cause hurt and complications and certainly lots od dysfunction, but it does not absolve our WAS of their accountability.
But, statistically 23-35% of all people who marry their affair partners stay married for life. I'm sure some of them are very happy about their choices.
Deep inside us we want justice and payment and consequences for wrong moral actions. We want to see it in our lifetime.
Sometimes we don't.
I think that will happen on Judgement Day, when all secrets are laid open.