aaaahhh!!~ I'm looking for an old manga where our female protagonist has a childhood friend whom she then finds out he's actually a delinquent (why do I remember him as a catboy). And, due to typical shoujo reasons, girl ends up kidnapped by rival gang and the "boss" falls for her and the two of them actually end up with each other.

Then, I'm pretty sure the childhood friend ends up in an accident and "lost" his memories. The rival calls out on his bullshit and says he's pretending so that the girl will care for him again.

Sorry if it's confusing!!! It's been so long since I read this manga...it's actually one of the first that I've read!

I think it might be Dakara ore ni shina yo by Minase Ai

Oh my god, it is!...Now that I've read it again, the MC is really terrible ...But, thank you anyways!!!