The novel's really long, 6 vol in total. Haeyoung is obsessed with Haewon. I think he's not gay to begin with, but fall for Haewon only, since their student day. Haeyoung wants to keep Haewon at arm's length, like a fish in a tank. But Taegyeom starts blackmailing Haewon for sex, then Haeyoung gets jealous and wants to punish Haewon. He's pyscho so in his mind, he just let the others two borrow Haewon for the time being. That's what I take from the novel (machine translated version thou).
Tbh I don't even think he is gay at all. I mean I feel like he just likes the control and power and if he would only fuck (in this case rape) MC and would be disgusted if it was another guy. But hey I might be wrong but with THAT type of fucked up personality I also might be completely right
Haeyoung did get jealous when he saw Haewon fucked/on top of the tan dude. Before all of that, Haewon is 'to look but not touch' thing.
Someone give me an indept spoiler please!! Do any of this pieces of irredeemable shittiest of the shits regret anything? Does uke run away? Also what is their motive behind this especially the seme!! (╬￣皿￣)凸