looking for a manhwa

i can't remember the title but i read it a while ago
the fl had an ex (red hair i think) and they broke up cos the guy was gaslighting her and shit, and he was cheating on her with her stepsis(?) or adopted sis (idk)
and a ml with dark hair he was like the top student or something, he plays the piano
and then there was a guy with blonde hair that was like a celebrity ish and he lowkey likes her too
help me i can't remember the title and i wanna pick it back upㅠㅠ