It’s the oldest story in the book: boy meets girl. Boy and girl fall in love. Boy and girl live happily ever after.

The problem? The girl in this instance is a computer, and the boy is the lonely Theodore Twombley (Joaquin Phoenix). Theodore, who spends his days composing love letters for other people, is slogging through the aftermath of a failed marriage when he purchases an artificially intelligent operating system. His drab life, backlit by a vaguely futuristic Los Angeles, becomes anything but with the addition of “Samantha,” as its perky O.S. identifies itself (voiced with flirtatious good cheer by Scarlett Johansson). The brainchild of writer-director Spike Jonze, “Her” is a bittersweet pondering on what it means to love, and love well, in the technological age.

It is oddly touching to watch Theodore fall in love with Samantha, and he quickly discovers how to be happy again. But can happiness be found with something that doesn’t exist, at least not conventionally? Is a relationship real if it doesn’t line up with accepted standards? Theodore tackles these issues thanks to a pointed statement from his ex-wife Catherine (Rooney Mara), and the gentle musings of his friend Amy (Amy Adams).

Although the movie stumbles in spots –you never entirely forget that Johansson is the woman behind the curtain, so to speak – “Her” demonstrates that love can be found in even the most unlikely situations. It is a poignant reflection on love and loss.