yknow, first I thought she broke up because she wanted to protect him, cause she will go on adventures where she can't protect his weak ass, but moments later she was alrdy sucking someone elses dick so fuck this bitch, you deserve better MC.
from what i see Mars reaction is more of hate than bully (i mean he hate those who don't try to fight back )....don't know and but he don't strike me as an evil bully we often see.
to be fair he probably focused most of his time to keep up with her level instead of you know actually supporting her , for now i wont judge any of the character but i got my bet that its an edgy revenge story and best friend is an a hole because idk mate cliché