I saw this movie a long time ago. Kinda liked the style of it even though I really disliked both characters (well mostly Summer...she was really obnoxious). Not the greatest movie, though it was...refreshing I guess, to see a more realistic relationship than usual.
eNTP might fit the best for Summer though I could see intp/infp/istp. The guy seems infj, could be infp/isfp/isfj.