Responses
Sangtae has Frollo syndrome he has feeling for Jinwoo, but he can't express them because of social issues with peers and Korean Homophobic society thus he develops an " I hate you, but I love you and Be mine or suffer " towards Jinwoo.
Tbh, I feel bad for Jinwoo. Sangtae is an asshole for overshadowing Jinwoo success just because his family is fucked up. He not only fucking others people's life but he also mentally torture Jinwoo.