@bibliophage I know it isn't, but you have to understand that OG Sihyeon's basically fall in love at first sight and grow obsessed with Jaeha.
Spoiler!
He's quite literally blinded by love. Jaeha, meanwhile, never loved him; in fact, he quite literally hated Sihyeon. It was precisely because Sihyeon was like this that Jaeha was willing to manipulate Sihyeon's feelings, accept his confession, and pretend to be his boyfriend, because he doesn't have to coerce Sihyeon or do anything, and Sihyeon will do anything for him, even if it means being paraded like a s** slave to rich clients and being abused himself. To be fair, OG Sihyeon was at fault himself for continuing to follow the guy who clearly never liked him from the very beginning until his end, but it's just that he's too pitiful that no one around him could blame him. His level of devotion too Jaeha is abnormal and unhealthy. You see in this chapter that OG Sihyeon was originally well-liked in the group, but remember the cold atmosphere with OG Sihyeon we saw previously from the members' memory? Basically, the member basically begged Sihyeon to share his problems with them, but OG Sihyeon refused to involve his members.