Any where the the leads are childhood friends. The male lead loves her, but must deal with the fact that another guy is in the picture. She only see him as a childhood friend and that brings him agony. Eventually the female lead realizes her love for him and they get together.
Preferably the male lead doesn't have another love interested besides the female lead, but the female lead does.
Seen:
In time with you (Taiwanese and Korean versions)
Fight for my way