Paul Giamatti watching porn is one of the most wrenchingly human things you’ll see on screen this year. This heart-rending spectacle happens just a few minutes into Tamara Jenkins’ “Private Life,” as Giamatti — playing 47-year-old theater director Richard Grimes — sits alone in a small white room in the Manhattan fertility clinic where he and his wife (Kathryn Hahn) have come in a desperate bid to conceive. His job is to produce a sperm sample. On the TV screen mounted against the far wall, an adult actor can be seen pile-driving his co-star, causing her to moan loud enough for everyone in the crowded waiting area outside to know what Richard is supposed to be doing in there. Jenkins holds on a close-up; exasperation, futility, and shame are written across Giamatti’s face like subtitles. Has it really come to this?

As the scene continues, it’s like a vintage Charlie Chaplin bit in slow-motion.