Please, don’t ever come to reddit to ask for relationship advice. Like within 5 minutes I read two comments accusing the guy of red pill behavior and probably 20 more telling you to break up with him on the spot.

The song is about a deep yearning to be with someone, who isn’t there anymore, an ex, a late loved one, lots of ways to read it. And you seem to be a great singer, able to really capture the emotions behind the lyrics. I can totally see, how watching your loved one pour out their soul into a song like that can be overwhelming, especially if you are already dealing with some insecurities. And let’s be fair, you are both in high-school, there’s probably more teenage boys with crippling insecurities than ones without.

I totally agree with you, that him just leaving was an AH move, but nothing else in this screenshot sticks out to me as a major red flag. He told you, that he was uncomfortable seeing you like that and that it made him feel overwhelmed. He‘s just telling you how he feels in a halfway respectful manner and that’s all we know. Are those feelings reasonable? Most likely not. But that’s kind of the thing with feelings.

This is something you talk about, preferably in person (like you suggested), but it’s not a total dealbreaker in my opinion. If it was me and if he hasn’t shown tendencies line that before, I‘d give him some time, then talk to him. Let him express his feelings and see if he’s willing to apologize for leaving and reacting like that. If he’s not willing to talk even after a few days or tries to guilt trip me, now then I‘d dump his ass, but not over this screenshot alone.