By AMY BIANCOLLI

Houston Chronicle

The End Times are a tricky time for love: that’s the gist of “Seeking a Friend for the End of the World,” a half-tender portrait of two very lonely hearts in the closing weeks of humanity’s run on Earth.

This is a strange movie. It’s strange because Steve Carell almost never cracks a smile - not much beyond his eyes, which convey a sadness and a soulfulness last fully realized in “Little Miss Sunshine.” It’s also strange because writer-director Lorene Scafaria shifts tone midway - straight from withering cynicism and apocalyptic-orgy gags to honeyed meditations on life, death, the one who got away and the fickle timing of Eros (he’s sometimes compulsively early, sometimes compulsively late).

Carell plays Dodge, a defeated insurance salesman whose wife (played, however briefly, by Carell’s real-life wife Nancy) bolts the car and his life when a radio deejay announces that “the final mission to save mankind has failed” and then segues into the Beach Boys’ “Wouldn’t It Be Nice.” Twenty-one days before a 70-mile-wide asteroid is scheduled to cream the planet, Dodge finds himself terribly and definitively alone.

This is the film’s most interesting, convincing and darkly comical stretch, this period of disorientation as Dodge shows up for work (“feel free to wear your casual Friday clothing,” assures the boss) and putters through his life in the absence of hope. Carell being Carell, there’s a thin film of fatigued moral irony lining Dodge’s gaze as the folks around him chuck scruples to the wind and greet Armageddon as an excuse for Boschian excess.

And then there’s Penny, the blithe spirit played by Keira Knightley in one of her least affected performances. She shows up weeping at Dodge’s window, right when he’s mooning over a lost love. Soon they embark on a pre-apocalyptic road trip: He to find his beloved, she to see her family. The light in her eyes, and the moistness in his, tell you all you need to know about their quest.

Sweet and serious as is, the second chunk of “Seeking a Friend” is the lesser of the two - and hard to reconcile with the more acidic comic outlook in the film’s first half.