Oh well, guys, you know how things tend to go in manga/anime, don't you?
Main characters have some sort of "imprinting" on "first girl" and they will always keep their eyes set on her, THE ONE they liked at beginning.
No amount of kind gestures, exceptional accomplishments or noble sacrifices will ever bring to the other girls anything else than heartthrobs and bittersweet tears.
They will spend themselves longing for a MC that will never reciprocate their love.