From what I can tell they had something going on between them during their military service and then the mc left him
He had a crush on sihyun during military service, then during weekend leave, he tried to kiss sihyun after drinking(they were staying in a hotel room together) , and then sihyun clocked him. From what I’ve gathered, sihyun has been cold and a pain in the ass to bottom(I forget his name), but I think sihyun is mad bc bottom took his first kiss, then acted like it was no big deal. I think. Honestly it has been hard to follow especially bc they look SO similar and there has been no communication （￣へ￣）
During military service, mc is a closeted gay who instantly was attracted to ml's pretty face. However after he had a wet dream about ml, he felt guilty so he began avoiding ml. This caused rumors to spread that mc doesnt like ml.
ml on the other hand is a rich kid who's the child of a mistress. Durinh military, he does what is expected of him but keeps to himself basically. After a senior cadet began bullying ml, ml retaliated, but in order to keep the "peace", mc stepped in and gave ml a hard time just so the senior guy will back off and stop actually bullying. Anyway, ml is aware that mc treated him harsh in front of others, but behind the scenes, was making sure he is taken care of so he was a little confused about mc in general.
During their break, mc and ml ended up spending time together and got drunk at a motel. That's when mc kissed ml. ml obviously was shocked and punched him. But this then angered mc so they just kept egging each other on and ended up making out. During this tussling, mc pressed against ml's neck, choking him and he got hard, mc also bit his tongue for punching him. This awakened ml's m-tendencies. mc later acted like none of it happened, which is why ml has been so hung up on it ever since.
If I remember well (my memory is bad so maybe the story gets a little distorted):MC had a crush on ML (Sihyun) and when they were in the military, while drunk MC kissed ML out of nowhere (they had almost no relationship, they were not even friends i think). Next day MC forgot about everything but ML does not know that he does not remember and thought that MC was a b*tch taking advantage of him and has thoought that since then. Back in present, Sihyun still thinks that ML is "loose" and that is why he treats MC that way. As I said, MC does not remember kissing him, That is why he does not understand Sihyun's attitude towards him. So... more missunderstandings keep accumulating
Can someone explain the history they have with each other I’m so lost