If it weren't for the fact that he:
Lied multiple times
Acted like a spoiled shit coming along just to see a breakup
Undermines the work Yoon has done
Put the blame of his eventual (he knows this is going to end badly from the very beginning) breakup
Yet YET HE COULD'VE BEEN A GOOD CHARACTER DESPITE ALL THIS BUT HE ISN'T. HIS MOTIVATIONS DON'T MATCH UP? Like he has put forth this image that what he's doing is being there for Taejoo with Yoon gone because he loves him but he lies to him so they can be together? Like imagine you accidentally sleep with the friend you have a crush with, them drunk but they don't remember anything other than the fact they didn't want to do the deed. You like them but they regret it thinking you mightve not given consent. You have but a. You want them to feel guilty for committing a crime for the rest of their life or b. You honestly tell them you did give consent and everything is alright.
I honestly don't think Youngwoo loves Taejoo and honestly, I pity them all.
Get a room for you and your ego.
I get that that those two are a-holes but you are outshining em right now.
Never forget them.