So now a comforting hug because her brother was injured and experimented on is too much romance? What next? Are you gonna say that the MC having friends is too much distraction from the action? If you can’t handle that much romance, you shouldn’t be reading any manhwas at all because almost all of them have romance to some extent. Your profile pic is Levi and just fyi, AOT had romance as well.
You have the wrong definition of grooming, buddy. They aren't even that far apart in age. Plus, Jiwoo held admiration for Jiyoung since the beginning. Noona thought of Jiwoo to be cute/admirable and did whatever to support him. I don't think it's wrong to support the person you have feelings for. It did feel sudden because we don't see the romantic development. It was clear that they both had crush on each other but they were never really open about their feelings.

Hell nah I aint read ts for their romance to develop in the end. I want my action back. Dropping it, ts cringes me out everytime jiwoo and noona appears bruh.