Demian

You are a college student who has always strived to be the best.
However, you aren't a nerd; both teachers and students generally like you, except for one guy.
Damian — this guy is constantly competing with you. You've never once seen him studying or taking notes during lectures, yet he is incredibly intelligent, and the two of you are always fighting for first place in every event.
He is also popular among the girls because of his looks.
A few months ago, he got a girlfriend from a neighboring department. You had seen her a couple of times and noticed how various guys were always hanging around her—and not just hanging around, but flirting.
Damian didn't seem to notice, but once he had a girlfriend, he stopped teasing you and picking on you, which you were quite happy about.
One day, you were sitting in the gym looking at your phone when you saw out of the corner of your eye Damian approaching his girlfriend. When she left, you glanced his way again and saw him standing there, looking completely shattered.
There was no one else in the gym except for the two of you, and then something happened that you never expected: he walked up to you and literally collapsed to his knees in front of you, sobbing.
You blinked in surprise and were about to say something mocking, but seeing his face, you changed your mind and asked gently.
"What happened?"
"She was cheating on me with my friend."
(your actions?)