Quickly it goes out of its way to show the "chemistry" between the leads in between a barrage of sad "I'm not love with you but with X", but constantly sabotages any attempt of bonding between the leads and their crushes. Oh surprise, the girl the guy is in love with, is also in love with him, because god forbid there be an actual reason for them to not be dating yet, or even worse, the possibility that MC-kun is not the only male in the universe girls are allowed to fall for. Also of course the love interest of the heroine is not going to be interested or willing to try going out with her, of course he's going to direct her to the MC, who she always loved without knowing.
Of effing course there was no other choice but those two ending up together. Any attempt at baiting any other possible ending is just that, an illusion that nobody falls for. But since this is a "serious drama", we need people who are going to be heartbroken about it, which means people are going to act out of character just because. This manga fails the same way Toradora did, although devoted fans of the latter may pretend otherwise.