In the visual novel Edelweiss, not choosing Natsume's route might count as a fridge horror moment. In Natsume's route It's revealed that the Natsume you meet isn't exactly real, but trapped in some sort of other world, in the Natsume route you free her and you both make it back to the real world, everyone's happy and stuff. However...since you did NOT play the Natsume route then it's assumed that Natsume is still trapped in that world, further evidence of this is shown when Natsume disappears from the other heroine routes. Made even worse when everyone just kind of forgets about her...
Ran's route. Wait, what's going to happen when the Principal comes back from the mainland and sees Kazushi and Ran basically destroyed everything she has been working on for the last 50 years?
Also, they mention that the fact that Mei, the Homunculus, is still alive is a miracle on itself. Even if Kazushi doesn't make her fall in love with him, her very existence is hanging on threads. So, in all the other routes, Mei's also going to inevitably vanish, probably without even knowing why.