They aren't in a relationship. At one point Hanjun thought they were but Jaeha said they aren't. Hanjun wishes they were tho..
Ah, so they're friends w benefits? Still, Eunho thought/thinks that they are, regardless.
As someone who's cleaning some of the upcoming chapters, I can tell you Eunho knows/thinks they aren't in a serious relationship. The one thing he truly wants from Jaeha is for him to stop seeing him as a child because he isn't one anymore, so it's unfair for him to be treated like a kid no matter the emotions involved.
Additionally, I'm not sure where you're getting Eunho is forcing Jaeha to accept his feelings? Eunho distanced himself from Jaeha because he knew Jeaha didn't feel that way, and yet it's Jaeha who keeps reeling him back in.
Everyone hates Jaeha... but I despise Eunho. He continues to pursue his crush despite his crush already being in a relationship... it's rude and disrespectful. Now I'm starting to dislike Jaeha for not even breaking things off with Hanjun... but Eunho has no respect for other people's feelings either. You can't and shouldn't force people to like you!