wait, im confused. what happened ?

I think that the guy jungwoo went to beat up is the guy that broke youngmins arm (unless its a just misunderstanding and youngmin broke his arm some other way)

yeah is a misunderstanding, he broke his arm trying to see jungwoo again ;(

He beat up the guy that started rumours at the workplace before because he thought he broke youngmins arm. But Youngmin broke his arm trying to climb a wall to get to Jungwoo so yea it's a misunderstanding.