So she basically saw him water plants and clean the blackboard a few times, and that was enough to make her fall in love. She literally knew nothing at all about him. It feels kinda hard to believe, but I guess it's not impossible that someone would develop a crush like that, but that just makes her seem kinda shallow. I think it would've been quite sufficient if she fell in love with him because of what he's done since he broke up with Hanabi, some of that stuff is genuinely impactful. But making her having been in love with him since before just makes it less believable. It feels a bit like those romcoms where a guy meets a girl seemingly randomly, they gradually develop a relationship through various events and incidents and it feels like they are developing feelings for each other in a natural way, but then as we start getting close to the confession it suddenly turns out the girl is like this childhood friend that the guy forgot and that she's been in love since they were five, and it feels completely superfluous because it retcons her entire character arc for the sake of a boring, shallow plot twist.