I'm sure I read somewhere that she actually likes him and is completely committed to a relationship with only him even to the point where she gets super jealous of his sister being so close to him, though im not sure why he doesn't use his future knowledge other than he possibly has changed the timeline and the future is completely different.
@semon_demon for the future part
wasn't the MC an adult before, i'm pretty sure you won't remember but the key events of your youth if you were to dig your mind looking for knowledge so that's probably why he don't use that magical future knowledge (at most he could remember if somebody killed himself due to bullying and he could step in but that would be too cliché isn't it)