Responses
Might not be 100% accurate as I kinda forgot some details. Spoilers ahead!
Basically Yoon was MC's friend from his previous life/real world. He was the reason mc isekai-ed because I think they had a fight and he was mad? Not really sure, kinda forgot why. I also forgot if he directly said that he's mc's friend or if he's just from the real world. Anyways, he'll end up blackmailing mc to kword himself in order to leave this fictional world and help bring back the og mc of the story's (ml) life together. Obviously mc died but he returned to the book and got together with the ml.

I feel like I’m in the minority of Jaewoo ending up with Mr.Yoon it’s just funny asf to me how silly it would be