If you have to stop to think about the answer to the question, “Whom do you like better, your spouse or your dog? — and don’t act as though the thought hasn’t occurred to you more than once — then “Darling Companion” will have no trouble wagging its way into your heart.

A gentle, winning comedy about a Denver couple who have drifted apart, Beth and Joseph (Diane Keaton and Kevin Kline), the movie takes a simple if shattering occurrence and uses it as a way to bring a family together. It’s an old trick but one played well by director Lawrence Kasdan and his wife and screenwriting partner, Meg.

The event in question involves a runaway dog named Freeway, a mutt Beth and her daughter Grace (Elisabeth Moss) rescue from the side of the road. Joseph, a busy, distracted surgeon, objects to the idea of a pet, but there’s never any real question that Beth, lonely because both her girls are grown and living their own lives, is not about to dump the dog at the pound.

So Freeway is absorbed into the household as a treasured member of the family. Then, a year later at Beth’s wedding at the family’s gorgeous Rocky Mountain vacation home — Utah does a spectacular job standing in for autumnal Colorado — Joseph takes the dog out without a leash, and while he’s talking on his cellphone, Freeway runs off after a deer and doesn’t return.

The rest of “Darling Companion” focuses on the search for Freeway, undertaken by a distraught Beth and guilty Joseph; his free-spirit sister Penny (Dianne Wiest); her jovial new boyfriend Russell (Richard Jenkins), whom Joseph suspects is taking advantage of Penny; and Penny’s grown son Bryan (Mark Duplass), who doesn’t trust Russell either and finds himself drawn to the vacation home’s caretaker Carmen (Ayelet Zurer).

Carmen takes the search up a notch by claiming her gypsy ancestry allows her access to visions that Freeway is not dead. This assertion sounds ridiculous until you realize that whether Carmen is actually clairvoyant is beside the point: Her goal is to bolster hope because as long as there’s hope, Freeway remains alive.

This slight plot is an excuse to allow the various characters to warm up to or make amends with each other. Practical doctor Bryan finds himself trusting the unorthodox (and beautiful) Carmen; he and Russell have an adventure that bonds them in the way only comically terrifying experiences can. And of course the real relationship in need of repair is Beth and Joseph’s; they have to move past anger and frustration as the search drags on to some sort of understanding and acceptance about what the rest of their lives will be like.

“Darling Companion” has a light tone that should reassure animal lovers that there’s no horrific “Marley & Me” scenario looming at the film’s end, but the Kasdans do get the anguish of a pet owner in distress just right. Joseph tells Beth that he feels bad, but “we haven’t lost a person; we’ve lost a dog.” Her tearful reply cuts to the bone: “Love is love. It doesn’t matter if it’s a dog.”

You don’t have to love dogs to enjoy “Darling Companion,” but it couldn’t hurt.