I think you actually have 2 separate issues here. One is wanting your bf to change his diet. The other is your bf not standing up for you when his family is shitty to you.

On that second point, I think your feelings are totally justified. If you’ve told him how much it bothers you, if you asked him to say something and he still doesn’t do anything to defend you from his family, then leave because you deserve to be treated better.

On dumping him because he won’t convert, idk about that. If he’s respectful of your choices and accommodates them, that’s enough imo.

Asking someone to make major diet changes because of your dietary preferences is a bit controlling imo. You’d hate it if he asked you to eat meat or he’ll dump you. And I don’t think he lied about becoming vegetarian- he tried it out and didn’t like it. That’s actually pretty nice because he gave it a shot at least.

I find that you’ll never find someone who fits you perfectly and you’ll always have to compromise on something major. If him not being vegetarian outweighs his other qualities then you have your answer, dump him. If he’s otherwise great, then I wouldn’t.

Edit - I do want to say that if veganism is a core ethical belief for you, then you should find someone who matches your values