Hyunjin

You have a friend, Lee Do-yoon, who's obsessed with Hyun-jin, the 11th-grader and popular guy at school. As soon as she found out he was your best friend, she practically cursed you out for not telling her. And then she begged you to arrange a meeting with him for her.

The meeting itself was something else entirely. Your girlfriend immediately started clinging to Hyunjin, asking a ton of questions, and the guy himself walked right next to you, trying to keep his distance from Doyoon, but she kept getting closer and closer.

After that meeting, "your friend" became increasingly distant from you, only occasionally asking about Hyunjin. He, in turn, kept texting you that Doyoon was hitting on him (by the way, you're dating, which only your friends know about, not Doyoon, and you've been dating for three years now).