Pretty sure that guy is the Hyung Jaewoo was secretly hooking in the main story. The one he kept hanging because he was in love with Ohn. I would have looked their story progression but I can imagine how it went. Heartbroken Jaewoo was helped by this guy and he finally fell for him.
Geez calm down !!
Your so OTT if you payed attention in the main story you would know who jaewoo's man is, and secondly this side storys hole theme was to focus on both our male leads intimate progress as there was none in the main story and thirdly there is a side story come out soon about jaewoo and his bae which is why there was only hints of his story in this one you need to pay more attention instead of jumping to conclusions and crying about jaewoo you should read the main story again it's super obvious our male lead wasn't going to end up with jaewoo
Would've been nice if the story isn't focused on Ohn and Seo woo fucking, instead it should've been about Jaewoo finding his partner, but what do we got? A random boy as his partner just to satisfy Jaewoo's fans.... LIKE NO IM NOT SATISFIED!!!!! The author barely showed Jaewoo in the side chapters and the last ending??? "They've been planning their wedding" oh wow Im sa thankful he's getting married with someone who's not so relevant(╯°Д °)╯╧╧ Like thanks author for the 'satisfying ending' it made me so happy to the point where I wanna smash my head to the wall(≧∀≦)