First of all, don't paint this like I'm having some kind of unreasonable fit. Second, are people not allowed to express dislike for stupid fiction tropes, now? "Character A likes Character B, and expresses this by physically and emotionally abusing them" is a shitty, unsatisfying premise, and only gets worse the older the characters are.
guys its a manga with a fetish for mean girls. if you dont like it then dont read it, dont waste your time typing paragraphs in the comments and wishing she would get hit in the head by dumbbells, it aint happening