Responses
i thought that at first too, but if you really paid attention to senpai's dream/memory. He was already in love with her from the beginning. He only started treating her as a love interest, when others pointed out that he was in love with her. He's honestly the one one that didn't look at her outward appearance as "better," for his personal reasons throughout the whole manga.
In the end this is a love story about two incredibly dense people who probably wouldn't have gotten together if she hadn't lost weight and attracted a bunch of love interests.