Don Jon, written and directed by J Gordon-Levitt is the cautionary tale of how porn skews the idea of what sex is supposed to be like. Gordon-Levitt plays Jon, the guy who prefers porn to real sex comparing each sex act from real to porn with the real sex coming up short on its fabulousness. He has plenty of real sex but while the girl is sleeping, he goes to watch more porn.
He finds a girl he genuinely likes, Scarlett Johansson who was made to look perfect from every angle. She flips out when she discovers he watches porn but she has her own porn: romance movies. She imposes her own idealized fantasies on him and the relationship ends when she discovers his browser history filled with porn.
Repetition is the vehicle for this story. There are repeated scenes of Jon going to church, making his confession (e.g. sex with 2 women out of wedlock and masturbated 15 times), receiving his penance, going to Sunday dinner at his parents, going to the gym and saying his penance while he lifts weight. His sister is texting or rolling her eyes through every scene so when she does say something at the end of the movie, you know she has the clear view of the situation.
Jon does learn that sex can be different from porn in an unexpected way, that porn is not sex. Fun, interesting, thoughtful.