Marisa Tomei and John C. Reilly star in the movie 'Cyrus'

In “Cyrus,” John C. Reilly he’s is John, a sometime editor and layabout who, after seven years, is still reeling from his divorce. (He was dumped.) When he finds out his ex-wife (Catherine Keener) is remarrying, he goes into a tailspin but, in a deus ex machina moment, the woman of his dreams, Molly (Marisa Tomei) comes up to him at a party, and pretty soon they’re a couple. The catch: Her live-in, 21-year-old son Cyrus (Jonah Hill), Molly’s best friend and, as soon becomes obvious (though not to Molly), John’s worst enemy.

Cyrus is written and directed by the brothers Jay and Mark Duplass. Reilly doesn’t go for the obvious laughs. John’s ardor for Molly is actually quite touching, which is why, when Cyrus threatens to wreck his elation, he’s both bereft and enraged.

“Cyrus” slows down by the end, and even before then it’s often too mopey for its own good. But there’s an original comic temperament at work here, and that’s rare. Grade: B+ (Rated R for language and some sexual material.)