I guess the point of this movie is supposed to be that as we grow up, we have interactions with each other that are awkward and melodramatic and which can end badly, because we're unable to be honest about our feelings or considerate about the feelings of others. And once we grow up, we can revisit those feelings and realise what motivated the way we behaved when we were younger. But I think there are probably better ways to express that idea than by writing a story where a girl who is impossible to like (seemingly on purpose) jerks around the nice, kind, totally normal protagonist for 40 minutes, only for us to find out that they were really in love the whole time once they have a post-high school reunion.
At least it looks nice.