Okay, basically the story will progress to Hajin getting the memories of Sihyun. Daejun all ready knows he's Hajin in. Sihyun's body but will be actually confirmed when Hajin got all Sihyun's memory. Daejun is actually the one who will be the ML, no one else not Chan or that actor-no chance for them since the start. Then once that memory came back, you'll know how Sihyun suffered from his exboyfriend Jaeha, the leader of that other group the blonde one. He's basically being sponsored, lots of scandal and dragged Sihyun into it, in the excuse of love. Sihyun love Jaeha, despite not liking it he let Jaeha have sponsors - actually he already have one before they got together. To make the story short. Jaeha, drugged Sihyun beyond his consciousness that hevwas being sexually used and raped over and over again by some big shots or sponsors, like for that days he was drugged and not aware of his surroundings. Thst caused his psychological diagnosis hence as stated in the current chapter. His group didn't know about any of it that's why he is being alienated. Sihyun is just so pitiful, no one ever did reach out and cared for him. He thought Jaeha loves him but in truth Jaeha is faking it.
MC, the past him is so pitiful, he's been hurt beyond words. Daejun boy will be there for him until the end, solving past Mc's conflict and protecting him. You'll be surprised about the OG Sihyun's perpetrator, he deserve everydownfall he will get in the future.