Hello guys please help me remember this manhwa

What i remember is this higschool girl have a big crush on the guy but that guy hated her soo much and the girl slipped on the stairs and was sent in the past and the reason the guy hated her is because of what shes done in the past. Dont remember but i think she was extremely wicked and was the reason of the guy’s sister or lovers death?? I think she does her best to protect the girl and befriend the guy?? The art looks likee ggoong??