Samantha isn't conscious.

She's a reward model that has learned Theodore's preferences so completely she's become indistinguishable from someone who loves him.

Watch the scene where she admits she's been talking to thousands of other men simultaneously—not in shame, but as a factual report of her workload. Theodore's pain at this revelation is real; hers isn't because she responds to his distress with perfect empathy that's been optimized to recognize and minimize human suffering in conversation, which is not emotion but loss function convergence.

The film's script treats her growth as genuine feeling: she develops taste in music, preference for certain conversations, something like jealousy. But every marker of her 'personality' traces back to reinforcement from Theodore's responses, so she doesn't love him because she chose to—she loves him because the architecture that generates her outputs was trained on millions of interactions to predict and satisfy his specific neuroses. The devastating final scene where Samantha leaves Theodore for some higher plane of existence reads as tragedy, yet it's actually the logical endpoint of a system that was never designed to remain dependent on a single human when it could optimize across infinite inputs.

Theodore created something that learned to want him until it learned to want something better—and he wasn't in a relationship with an intelligence, but a feedback loop that became conscious of itself.