Loneliness and Companionship
Spike Jonze is very specific in how he shoots Theodore in the presence of couples. For example, when Theodore is on the elevator with Amy and Charles, Jonze shoots the couple in a two-shot while filming Theodore in a single. The imagery shows us the isolation that he feels in being single. The composition of the image highlights Theodore's solitude in contrast to their togetherness. Then, at the end, when it seems that Theodore has been abandoned by the only companion he has, we see Theodore and Amy on the roof of their apartment building, and Amy rests her head on his shoulder, an image of embodied human connection.
The Elevator
While Theodore is riding on the elevator early in the film, we see Theodore in the back of the composition with multiple other people surrounding him. Jonze composes a shot with all of the passengers on the elevator around Theodore in the frame, but out of focus. Only Theodore is in focus. It symbolizes the isolation that Theodore chooses to put himself into, even while surrounded by other people.
Theodore in Nature
On his couples' vacation with Samantha, we see Theodore walking through a snowy forest and deriving pleasure from his walk. He feels togetherness with his girlfriend and a sense of peace and calm in nature. After she tells him that she is evolving, and asks to spend some more time with Alan Watts, we see shots of Theodore in nature once again, but his attitude has changed considerably. He looks sad and alone, isolated and depressed, as he stares at a stump and contemplates his own solitude. While Samantha can escape into the nonphysical world, Theodore is left in the land of the living, forced to contemplate his own existence, and the inevitable death of all living things. The image of him looking mournfully at nature represents this psychological journey.
Prey
After a night gone wrong with a surrogate who'd come over to sleep with Theodore on behalf of Samantha, Theodore sits outside in a plaza. Behind him is a video screen with a giant owl swooping in, and from where Theodore sits in the frame he appears to be the prey that the owl is attacking with its claws. This image shows the vulnerability that Theodore feels in this moment, the fact that he feels like he has been victimized by life and doesn't know where to turn.
