Same. Red-head was bound to fall for MC due to being young and never having anyone care for him where he felt close enough to open up to. MC sees him as a younger brother but even if red-head confessed I never thought MC would actually see him as a ”candidate to date” on the same level as ML. They have a lot if history together and maybe they were bound to find each other again even if life seemed to pull set them apart (”the one that got away”). Red-head will probably have a bittersweet first love (bc MC is kind which will probably also feel cruel) and his feelings for MC might cause conflict in the relationship between MC and ML that they have to work though for better and for worse.
Is it just me? I never thought of gyeongchan(?) you know the red-head as a potential 2nd male lead. I always thought he was there just to mimic / give off the same vibe as and talk about the self-harming singer jaebom(?), the toxic ex. Not to be a romantic interest himself. But instead to bring the other dude into conversation. But maybe I am reading it wrong.