Joseph Gordon-Levitt wrote, directed, and starred in the story of Jon, who's addicted to porn. He gets more satisfaction from the computer than the parade of beauties he regularly beds with ease.
Scarlett Johannson is Barbara, addicted to girl porn: cheesy romance and princess culture, with outsize expectations of what a "real man in love" should do. Namely, everything the woman wants.
She's "the most beautiful thing he's ever seen," but Jon can't stop getting his satisfaction from online porn despite his promise to Barbara that he'll stop.
Julianne Moore is a fellow student in the class Jon's taking (at Barbara's behest), weeping in the school doorway when he first meets her.
When she sees him watching porn on his cell phone in class, she brings him some "better, old" porn.
Barbara tracks his internet history and knows Jon broke his promise, and she breaks up with him. This is a great disappointment to his father (Tony Danza) who lusted after her, and his mother (Glenne Headley) who desperately wants a daughter-in-law and grandchildren.
Jon has sex in a car with his classmate, who tells him that it's obvious that he learned how to have one-sided, objectifying sex from porn. She invites him to her home, where he senses the presence of another man. She tells him that her husband and child died in a car accident 14 months ago.
They have sex, the first time he has ever lost himself in the other person during the act.
As the movie ends, they are having a healthy, mature, not-getting-married relationship.