
Oh I get what you mean, but he still chooses the worst reactions possible. The man he loves lives with a little brother and never acted suspiciously. The little brother having feelings doesn't mean they will be reciprocated, have faith in your lover for fuck's sake... And Sunwoo never did a single shit that could have been misinterpreted, and didn't even intend to confess just to keep his brother safe.
Hyunjin selfishly assumed imaginary shits on his own and acted like a piece of crap without giving anyone any chance to prove him wrong.
Actually what I really hate is the absence of development in his attitude. He was detestable from beginning to the end.

I think there was some progress, kinda, in the sense that he became more up front about his emotions. It’s hinted that he’d even started to think about marriage and stuff too so I think the author wants us to assume that he’s finally letting himself love the uke. Plus sunwoo did do things in front of hyunjin that made him react so it wasn’t just one sided aggression! I just think you’re being too harsh, all the characters have their flaws after all.

What did Sunwoo do?
I must have missed something because I didn't see anything tho? The only "thing" from Sunwoo was him being all flustered after touching his brother to wake him up, his wild fantasy and of course when he indulged on acting a bit spoiled, but this was at the very end...
Even when he answered the phone call, he did it not wake him up (even if he was troubled by that invasive lover, he never went against him) and all along the story, he has known his place as a brother and Hyunjin's as a boyfriend, he never stepped out of boundaries...
Alright Sunwoo is an angel and Hyunjin is a piece of shit. I hate him. And not even in a good way, like I would hate a very well written character, I just find everything about him despicable.
It was a nice story though.