[When Theodore and Samantha have sex,] the screen fades to black, which is meant to indicate how intimacy can make it feel as though the rest of the world has faded away. We hear this literally in their voice-overs: "Everything else just disappeared," and "It was just you and me." But the black screen also helps show what it's like to be an OS, bodiless and floating. That is, it helps us, the audience, empathize too, with a kind of being we've never encountered before.
Jessica Gross
March 2, 2014