"Have your cake and eat it" comes to mind. Unfortunately, I don't think this will leave his system, which is a shame because you're clearly doing all you can to understand what he wants/needs. You sound like you're handling this really well tbh - a lot better than most people. He thinks he's seeing greener grass when all he needs to do is tend to his own turf. I hope he eventually sees that before he throws away a good thing.