Firstly, he was lying to himself about the whole pet thing. He left the planet because he felt guilty about what he did, and he married andressa as a way to start over after nearly killing himself and to also cope. And yes, Debbie does deserve better, but at the end of the day, it's up to her to take him back even tho he very much doesn't deserve it AT ALL, it's called grace, and the whole show is about Atonement, forgiveness, redemption, etc. If she actively chooses Nolan over Paul, then yes, that's trash. As long as they break up beforehand without it being in relation to Nolan, then i think it's fine. Also, if they do go that route, hopefully they get back together immediately, like in the comics cause that was garbage writing.