Your girlfriend is trying to manipulate you by lying about what veganism is. If she waters truly conceded about animal cruelty she wouldn’t advocate to make your cat homeless or put him down! She just doesn’t like cats so she’s trying to pretend it’s a vegan stance so that you think there’s something moral to it. She thinks it makes her stance stronger. Not only is this a horrible thing to do to you, but it’s also unconscionable to treat an animal like that. I firmly believe if she moved in with you and the cat.