Her is a science fiction movie about love. It’s about robot love, about love for robots, and it’s also not that fictional.
The story you already know: a sentimental writer (Joaquin Phoenix) falls in love with his OS, named Samantha (played by the inimitable Scarlett Johansson). His OS falls in love with him. Mayhem, hot sex, and crocodile tears follow. It’s great. If you haven’t seen it yet, stop reading now and go.