Normally that would be my answer too.
However, since this all started when she said something harsh/insulted him about his behavior. He might be targeting her. I don't think those hearts he put after her comments were about liking her.
I could be all wrong, but this sounds like something I went through with a boy while I was in high school.
He was really an awful person. Today I realize he very well could have had a bad homelife, and I'm pretty sure looking back he had some kind of learning disability, like dyslexia. This was back in the 1970's though. I don't know how it was handled back then.
Anyway, he was always acting out. Picking on anyone he saw as weak, or who made him look bad.
One day I walked into a class early, and there was him and one other boy, who was really really shy, slight of build, and was nerdy, way before being a nerd was cool.
The bully was just finishing up on the chalkboard this elaborate picture and verbage that was just so demeaning and hurtful to the shy guy. I mean, the bully had to have planned this out for a long time before executing it, it was that complex.
The shy kid was just sitting at a desk, mortified. Couldn't defend himself. This was something this poor kid was going to be known for the rest of the year.
I knew other students were about to come in, so I picked up an eraser and quickly did a few strokes over the worst of it, then started really fast erasing the whole thing.
Bully could hardly contain himself. I'm sure I told him he was an asshole or something.
From that point on, until graduation, this jerk targeted me every single day. He noticed I liked a boy (who I didn't realize already had a girlfriend), and somehow slip a note in my pocket which I'd find later. He would pretend to be that boy, telling me how much he liked me, and to meet him at such and such a place and time.
I never regreted standing up for that kid, but jerk was sure a daily thorn in my side.
This guy the OP is talking about reminded me of that.