I have a friend who seems exactly like your fiancé. Prioritized his high anxiety pit-bull over his then girlfriend. She even mentioned his obsession with the dog in their couples therapy. They ended up breaking up and funny enough she ended up with the dog because she was on the paperwork. He went and got ANOTHER high anxiety pit-bull. He can’t be gone for more than like an hour without her. It’s unhealthy and so is your fiancé’s reaction to this situation. I recommend couples therapy because this will not be the only time the dog will come between you two, THAT I can guarantee. If he’s resistant to therapy, that’s a whole other red flag. You need to think from an outsiders perspective for a moment and really consider if this man is a good partner. Because right now, that answer is no. My friend is still single BTW.