Y'all are forgetting that Jisuh has never shown any feelings for Sunyool,not even once. Yeah,the drama was interesting and all,but nobody can force their feelings on another person. They never had any romantic relationship,they slept together once because Sunyool was being too pushy and childish and you saw what happened. To me,it seemed like Jisuh made himself pretty clear with Sunyool. Otherwise,we've already seen that Heejae is pretty much sincere about his feelings,at the point that he gets nightmares because of what he did in the past,and Jisuh is comfortable around him,misses him and he even told Sunyool that he wanted to get serious with Heejae. Ok,he's still an asshole for his past,and maybe it's hard for people to change,at least in real life,but they're fictional characters we're talking about. So,why underrate a relationship between those two,I mean,they seem both pretty happy whit what they have. By the way,Jisuh is not some childish character that needs a fluffy relationship (like Sunyool,even if at the end of ch.41 he seemed more mature),he himself said that he was ok with Heejae treating him like a toy. But this is all in the past,things are different now and they are growing feelings for eachother pretty fast. Talking about Sunyool,a relationship between him and Jisuh could never work,because Jisuh doesn't have any feelings for him,and they simply aren't meant to be. He's not the type Jisuh would want to be in a relationship with. Sunyool needs another character that has yet to be introduced maybe,and who can make him turly happy (at least I hope so).
I didn't read all of what you said but I think I should clarify that the relationship I'm praising is the writing of Sunyool and Jisuh's friendship. The author portrayed something real and responsible, a good model of how to be mature and to make up and tidy up relationships and friendships with people you have or have had romantic or sexual feelings for. I think it was something very rarely portrayed and was very happy about that

I don't believe this is really the end of things with Sunyool. But even if it is their story is already leagues better than anything the author can write with Heejae. (even redeeming him is too messed up to me after everything he did)