My friend needs advice. He's 22 years old and recently got a girlfriend.

He texted me that following.

So I'm basically in love with this girl and we've been arguing a lot lately. Whenever she's upset over something it bothers me so much and lately I haven't been myself. I've been lacking motivation in the gym, I've been skipping meals and haven't been craving food at all, like the thought of food makes me sick. And everything's just been mentally bad for me and I can't help it. I need to get my shit together and start eating, lifting, and staying happy.

It's honestly not even major things it's just things that happen over social media that I get upset about like her liking pictures of guys... Or something that happened in the past.. Or little things she does that upset me and when I bring it up she gets mad at me for it. I'm just constantly worried and idk why I like her so much, my biggest fear is her breaking up with me. But I need to become myself again and stop worrying so much about that her and get back into my normal life. Idk why I can't eat and it's cause I've been stressing about her so much and i get anxiety from it.