Mine would have to be the part when they are away on the athletics camp and, both unable to sleep, they sneak out at night. The beauty of that kiss while watching the deer followed by the line on the beach "Let's just stay here forever" perfectly captures that hope and wonderment of that young first love.
My favorite was at the very end of the film, at the celebration dinner. The little knowing smile that Sieg's best friend gives him was just wonderful. In that one look he was saying "you're my friend, you will always be my friend, and it's okay--go!"
Lovely moment, lovely film.