Basically, it's better to have loved and lost than never to have loved at all. Although the focus is mainly on the rather disturbed (and I won't say harmless, because in typical American male fashion he readily resorts to violence as a way to resolve his problems) Enoch, the story is driven by Annabel, a vivacious young girl with a sad secret. That they are both good for one another is undeniable, even for Annabel's protective (but not overly so) older sister.
I wasn't sure how Hiroshi fitted into this until the end, and that realisation added much to the depth of the film. I won't say any more to avoid spoiling the journey for others.