To preface, I have seen this movie maybe five or six times now and love everything about it. However I have always been somewhat confused as to why Summer goes off Tom and marries someone else at the end of the film. I believe it is meant to be somewhat ambiguous as we see this movie from the perspective of Tom, and as result, we the audience are meant to relate to his confusion and surprise of Summer’s change of mind. My brother and I watched it again and this time I watched out for any clues and foreshadowing early on as to why Summer leaves Tom. Here is my theory. The film is rich in color. Scenes are dominantly one color with many shades of that color surrounding it. Tom is brown/auburn and any other shades of this color. Here is an example:
Whenever we see Tom, he is either wearing colors of this tone or his surrounding environment being dominantly brown. Toms eyes are brown also:
Summer on the other hand is blue. She dresses in blue, her surroundings are often depicted in blue:
Her eyes are blue also:
Whenever Tom and Summer are dating and Tom is spending time with her, we can see the general surroundings of the scene become blue. This represents Tom being in Summer’s blue world. He is out of place and no matter how hard he tries to be part of it he can’t, because she is blue and he is brown. No matter how much they both want it to work and how much she invites him into her world, he wont be accepted because they are two very different people. Lets look at the morning after Summer and Tom have sex. The scene is of Tom dancing and singing his way through the streets and parks with everyone around him dancing alongside him. Everyone that dances alongside him are dressed in various shades and tones of blue, while he is dressed in his beige and brown colors. Even the bird is bright blue!
This is the moment Tom enters Summers world, hence everyone being in blue around him. But he doesn’t belong: he is brown, and she will always be blue.
The above scene is yet another scene among many that show how when Tom is dating Summer, he is in her blue world. In this case, even when she is in his apartment, which was brown in tone before they slept together, is now blue.
When they split up, the color palette goes back to how it was before they started dating:
The scene where Tom bumps into Summer on the train on the way to the wedding and has coffee with her shows their pre-dating color pallet.
Strong browns and auburns, because Tom is no longer in Summer’s world, and we are seeing the entire movie through his perspective. Again at the wedding we see Tom is wearing brown/auburn/beige while Summer is wearing blues.
I think it’s clear at this point in the movie Summer has become aware Tom does not belong in her life. However Tom has not realised the same, leading the movie to its most iconic scene: Expectations vs Reality.
This scene is dominated by their pre-dating colors as well as each of them wearing their respective blues and browns. The surroundings are brown because as much as Tom is trying, he is not in Summer’s world anymore. He is in his own. His own brown world.
The final scene of the film provides the most supportive argument for this theory. Tom attends an architecture interview. The building’s interior is brown:
Tom is finally in the right place in his life. His colors finally suit his path: to become an architect. It is also here where he meets his next love interest, Autumn. Autumn is already in his world. Her world is brown, just like his. Her eyes, hair and skin tone are all brown in color.
The main colors of the Autumn season are, as you know, browns/auburns/dark reds/ and beige.
The main colors of the Summer season are blues and greens.