I read it but it's still ongoing when I finished it. I can't remember the title. So there is a guy who's been secretly crushing on his best friend. But this best friend already have a girlfriend and was planning to get married. They're both office workers I think. His friend invited him to his house to celebrate his engagement with his long time girlfriend. The friend then ask for a favour to practice his vow on him, he was plenty drunk and so as soon as his friend finished his vow, he suddenly forced himself on him and went all they way while the fiancee is in the room sleeping. That's where it all start and started blackmailing his friend with his fiancee spilling what happened, etc. In the end the guy attempted suicide after admitting his fault. He jumped from his window and ended up in a coma. His friend called off the wedding. And he started to realize that he had fallen for his best friend who's in a coma for a long time and still waiting for him to wake up.

Was it a manhwa??