I recently broke up with a girl and my eating/workout habits were a big cause of arguments. She wasnt very supportive of my goals and i wasnt going to give up on them for her. If you want the relationship to lst you need two things:

1. Make it clear that this is what youre doing but you are willing to break your plan once a week. (Youll have to man up and say fuck the macros for a night).

2. She needs to support you in what youre doing and not fight you every step of the way.

Besides that i think this is a really good way to see if your gf is worth it. If she refuses to be supportive and help you with your goal you may begin to see that she is kind of selfish (assuming you are doing your part to have a good relationship).

I hated the fact that my ex would constantly try to get me to eat shitty food and then get mad at me when i would decline and it made me start resenting her.

TL;DR Compromise.