The film tells the story of a young girl called Adele, beginning in her last year at school and ending about five years later when she herself has become a teacher. After a sexual encounter with a boy (presumably her first) she feels that she is more attracted to girls. She wanders into a lesbian bar and meets Emma, a woman four years older than herself. A relationship begins which lasts about two years. The film isn't clear about the passing of time, but I'm analytical and like to nail everything down.
For now I can only write about the things on the surface of the film. Even in today's enlightened age homosexuality isn't accepted in school. When the other girls hear that Adele has visited a lesbian bar they become afraid of her. Adele never really "comes out". Throughout the film she doesn't tell her friends and family that she's a lesbian. Emma, on the other hand, is openly gay.
I don't want to say much more in order to avoid spoilers. I'll just point out symbols that I'm sure mean something, but I'm unable to say what. Emma has blue hair for the first two hours of the film, but when the relationship begins to cool down her hair is blonde. Sure, that's in line with the film's title, but why? I can sense the existentialist undertones of the film, based around Jean-Paul Sartre's statement, "Existence comes before essence", but I'm not well enough acquainted with existentialism to comment further. Food plays a big role in the film, and there are repeated close-ups of people eating. This could mean one of two things. It could be a presentation of the absurd, i.e. that while highly dramatic things are occurring we still have to eat. It could also represent having to overcome our revulsion with slimy things, finding pleasure in that which disgusts us. Life comes from death; oysters taste best if you eat them while they're still moving.
The film reminds me stylistically of Eric Rohmer's films. For the first two hours there is no background music, except when for instance performers are playing music within the film. In the third hour we hear the first backing music being played in school, and it shocked me so much that I'm determined to find out what it means.