I’m sure I missed it but why did eunho say jaeha was in hell during their relationship ?

He was scared that eunho will deal with the same bullshit he has dealt with considering being gay , especially from his family

He was scared because he knows he isn't courage enough to fully accept his feelings or face the world , he isn't courage enough to be happy

He was scared and sad that those feelings might harm eunho and he wouldnt be able to ease the pain
He didn't want eunho to become like him , it is not fair but it is understandable if someone goes through shit for being gay , they wouldnt want anyone going through the same shit

He was sad and scared that eunho still has feelings for him and it wasn't mere childish act

He was scared being the adult one to cause eunho to face horrible things especially from his family

I think it's more bc Eunho was kind of forcing/throwing his feelings on Jaeha, and not really thinking about how Jaeha was feeling. Eunho, despite giving Jaeha space and time to sort out his feelings, still sort of put Jaeha in a corner. Jaeha was being forced to realize his flaws and try to get over them. Hence the Hell. Jaeha struggles with relationships, big time, as we all know, nonetheless Jaeha grew to love Eunho romantically, but he was so scared he would fuck everything up. Eunho didn't realize any of this until just now, and feels he has done a terrible wrong to Jaeha now. Personally, I think they are both love-sick idiots. But I still love them!