yes i agree he deserves a steady and healthy relationship not an awkward situationship were he feels like the other person is only there for sex. also its not related to your comment but let me just also say this there’s absolutely nothing wrong with an uke exploring their sexuality and enjoying spending time with other people other than seme specially when uke and seme aren’t even official. were already aware that ideum is a freak in bed. if he sleeps with other people other than jaeyi that is completely valid. and i dont wanna hear people hate him for that. lets not support this trope of the virgin uke who’s cherry got popped by a much more experienced seme and now has to only be with that seme because…purity culture. there’s nothing wrong with an uke slutting it out specially when their love interest was also sleeping around before meeting the uke. ideum and jaeyi are not boyfriends. there relationship is strictly physical regardless of what they feel for each other. now if they work that out then thats great! but until then let’s not forbid ideum from forming relationships with other people specially when he’s been closed off from the world for so long. i think THATS what he truly deserves.
But I just think this doesn't apply to Ideum. Sure, what you say is fine but just not in the case of these 2. We clearly are shown on multiple occasions that they are starting to develop feelings for one another, they are on the precipice of talking about exclusivity and going out and getting more dick would not better the situation. I mean what is the purpose of that when Ideun clearly wants to be loved not only fucked. It's his whole character - mom who struggles to show affection and love, his insecurities about his scar. There's nothing wrong with your idea it just doesn't really belong in this story and it feels like you're projecting.
With that being said, I follow my own strict rule of accepting the story as it is told by the author. If she decides to go that route (which mind you didn't even happen yet and you are already worried about Ideun being hated) I would accept it as fact, no hate towards the author, readers, Ideun but I will also analyze my feelings and if I feel uncomfortable I'll just quietly drop it.
But again what your worried about, what you want to happen - none of it happened yet.

u know what the brother is sus but im glad he had that conversation with ideum…more people need to tell ideum that there’s nothing wrong with him and he needs to just enjoy life cus he’s family specially his mom did not do that for him. also y is jaeyi so mad in the last panel lol. anyway i still want to see ideum and brother fuck at least once. sorry not sorry. i know some people here hate that idea but why should ideum be limited sexually to jaeyi when they’re not even together. its just a physical thing right? lol let our ukeful uke have all the dicks in the world its what he deserve hahaha