Responses
Im not trynna change your opinion but i think that the reason why he couldnt get over the younger bro was bc he had no one else there for him to give him a better relationship ykwim? The younger bro was isolating him and feeding his ego with mc's crush on him from such a young age, which probably caused mc to normalise that kind of treatment and view their relationship as something good. He had no one to change that view and so he probably started liking younger bro cus of that
He's just being a doormat for no reasons.
I don't see any reason why he like the younger brother. He mentions it too he can't go on like this but then go along with every whim of his. It's really giving the vibes that he's being controlled by the way this series is written and not that he want to.