in a nut shell, that namhyuk guy was in the same debut group as siyoon. siyoon was popular amongst staff and some little fans (due to him being handsome and talented in everything) namhyuk got jelly and copied everything siyoon did from his aura, attitude, and looks. (they go to the same hs) there's this rich kid who also kind of hates siyoon bc he's hot. so they team up to be friends w him and then make false rumors about siyoon in school and on the internet. they bully him(verbally and physically) too. so all of that, accompanied by siyoon's parents made him want to kill really himself. he was just a naive kid then, he really didn't deserve all that. That experience made him really messed up in the head. Thats all I remember, and its been a year so Its very scuffed
also the company didnt really help siyoon. that rich kid and siyoon fought(I think) causing the rich kid's mom to be angry, gave money to the CEO, and demand siyoon to be removed from the group(correct me if I'm wrong tho its been so long and I might switch up situations from diff manhwas)
TBH I've already completely forgotten what happened to Siyoon besides the fact that he was bullied and tried to commit suicide. And was framed for something? I've just been going off of context clues.