I think Yunjae had an inferiority complex. He was bullied and alone he relied on Hajun to not feel alone and therefore felt possessive of Hajun’s attention. He knew Hajun put him as number 1 bc of his injury and paid attention to him. I personally think that’s why he’s so upset at Sihyeon and Hajun’s relationship and also why he lied about his past and his injury. It appears he may have some feelings towards Hajun but bc he’s timid and afraid he never came out to say it to Hajun. As for Hajun, I think at first he thought he liked Yunjae because he was under the impression that Yunjae was the kid he met in the past. I think that’s why he was so confused when he started developing genuine feelings and affection towards Sihyeon and was trying to reconcile that with what he thought he should be feeling towards Yunjae. When Yunjae said it had nothing to do with him, I think Hajun finally took that as a closure to his past expectations and feelings he thought he should have for Yunjae. At the same time, I think Hajun also finally accepted that he does have genuine feelings for Sihyeon even if Sihyeon has not been truthful with him the whole time (which at that point he was very hurt about). In Hajun’s mind at that time I think he was increasingly hurt by the inconsistencies in Sihyeon’s story (he did just find out the Sihyeon may not be named Sihyeon and went to a conference in a different name, had an ulterior motive for being together with him, and may not actually like him, etc). Not that what he does helps with the situation in any way, but I can see why he acted the way he did and I can also see why Sihyeon felt the way he did. It’s all in all a huge situation filled with so many nuances and misunderstandings. But I’d love to hear your thoughts about it more!
I was re reading this. I'd like to hear other people's opinions, why do u think Yunjae is such a liar and even tho he knows he doesn't know shit about Hanjun from their childhood (since they only knew for a few minutes bc Hanjun thought he was shihyeon (kid) and held his hands and they took a pic, and that was all), they met again in high school and that is were they started to know each other for real, so why does Yunjae acts all mighty praying he knows "everything" about Hanjun since children? Such a liar, even to himself. And if he liked Hanjun (as it appears since he seemed pissed at Hanjun and shihyeon relationship) why he never tell anything? And the last one, why Hajun asked Yunjae what did he think about him dating a guy? And he seemed pretty disappointed when Yunjae told him it had nothing to with him. Why? I mean, I thought he was already crazy in love with shihyeon there, so why would he care what Yunjae thinks and look disappointed at it? And when he didn't want shihyeon to touch the pictures on the ground, why? I really understand why Shihyeon felt so insecure. Because so much things about Hanjun behavior made u think like shihyeon did.