Starring Joseph Gordon-Levitt, Scarlett Johansson, and Julianne Moore. Rated 18A.

In his writing-directing debut, Joseph Gordon-Levitt explores some potent, rarely seen territory without missing the comic possibilities of playing a fellow whose priapic tendencies bring him more pain than pleasure.

In Don Jon, the former child star and perennial almost-leading man is the buffed-out Jersey dude of the title, a bartender happy to hang out with his long-time wingmen (Rob Brown and Jeremy Luke), bang the hottest chicks around, and polish his bachelor pad to a dull sheen. That’s not all he polishes; he’s also been known to masturbate up to 10 times a day.

Jon doesn’t talk much to his All in the Family clan. His silent sis (Brie Larson) sticks to her iPhone while Mom (Glenne Headly) screeches at Dad (casting coup Tony Danza), who stares at his big-screen football. This downmarket foursome does come together for Sunday mass, after which the Don (as his buds call him) turns his weekly confession into penitence reps at the gym.

All good systems have their limits, though, and Jon’s routine founders when he meets Barbara, played to gum-chewing, booty-grinding perfection by Scarlett Johansson. She gets him hooked by dodging his one-night-stand scam. But once they couple up, there are some problems: she won’t tolerate his wanking habit and… Well, she doesn’t actually like much of anything about him except his genetic suitability.

Barbara sets out to remould him, with night school first on the agenda. But he gets more education than either expected when he keeps bumping into a frank-talking older woman hitting the restart button on her own life. This is where Julianne Moore, as the open-book Esther, takes over the movie and starts shifting Jonny boy’s priorities, even if he’s initially bugged by her boho ways.

Gordon-Levitt unfolds this sweetly raunchy tale with clever editing, smart twists, and a perfect cast. It’s a three-Kleenex movie—just not in the usual sense.