Book with abusive high school boyfriend?

Hi all, I read this book 10+ years ago and the details I remember are pretty sparse.

I remember this couple was in high school, and the guy has some sort of memory of pushing his girlfriend or something, leading to them breaking up, and he thinks shes overreacting maybe?

It is later revealed what he remembered as “pushing” was actually him beating her up pretty badly. i seem to remember him slamming her into a light post or something. Any ideas?