I'd say this film is an essay, regarding shyness, relations with the opposite sex, friendship and love. Being only based on the dialogues between different people, it's full of substance, and will definitely ask the viewer to think on the matter. I liked it so much because the people were real, the problem was real. Lots of people suffer problems of integration and self-achievement next to others and these have been thoroughly dealt with in the film.
Its main problems are how much is worth a summer romance next to a sincere friendship, and the importance of knowing exactly one's feelings and purposes (do I love her, or do I not ? Am I merely trying to have fun?).
In the end, we are faced with a line addressed to the main character that we can take for ourselves: "it was your own choice, think about it".
That's the main message: the director presents a problem, the dialogues delve deeply in several of its aspects but the conclusion of why things turned out as they did is left to us. In short, the viewer will certainly learn something from it, and that can even lead to deeper self-reflections on one's personal life. A valuable film, and an interesting lesson. Especially good for young people afraid of not finding that special one.