In the end this is a story about terrible people, if you are really rooting for someone here think twice about it.
The husband is probably the one least in the wrong, we haven't seen him do anything morally reprehensible, but more often than not he sucks at being a husband and a loving partner.
The main two also just keep on adding stuff to their wrong doings, at this point if they fuck or not it doesn't change things that much.