You've been suspecting your boyfriend, Jino, has an affair on you. One night, you secretly follow him and you see Jino making love to another girl in that girl's apartment.

You're freezing while you're standing in front of the door but you realize someone is also watching them with you.

It's Heeseung, he watches his girlfriend, Arin, making love to your boyfriend, Jino.

They're looking at each other and they know they're hurting when they see their lovers are cheating on them.