You are dating soobin's sister(Si-joon). Soobin is known for being a huge fck boy. He always finds a way to sleep with his sister's boyfriends. His sister begged him not to sleep with you because she actually likes you. He agrees. Soobin decided to make a bet with his friends. The bet was to get you to sleep with him. Obviously he was gonna break your heart after (boyxboy)

"She always chooses the gay ones." He muttered "Hello I'm soobin, Si-joons brother." He smiled