Four couples travel to a South Seas tropical paradise operated by a mystic guru who promises to mend fragile relationships in Couples Retreat. The only hitch: three of the couples don’t think their relationships need mending. They only came along for the sun, the snorkeling and the Jet Skiing. Boy, are they in for a surprise.

Couples Retreat was written by Dana Fox and costars Vince Vaughn and Jon Favreau, the actor-writer-director who helmed the fast-paced action film Iron Man. Well, maybe Favreau felt he needed a vacation in Tahiti after all that excitement.

Although Couples Retreat has a few laugh-out-loud moments, the comedy is decidedly on the lightweight side.

Surprisingly, as the four couples participate in mandatory morning sessions with marriage therapists, even the “perfect” relationships turn out to have more than a few kinks. Suddenly Couples Retreat becomes more introspective and brings up ideas that may make some ponder the soundness of their own relationships. Who would have guessed?

The script gives a spectrum of situations. Jason Bateman (of Arrested Development) and Kristen Bell (TV’s Veronica Mars) are Jason and Cynthia, the couple whose marriage is foundering. He’s a control freak who always tries to steer Cynthia to his way of thinking. They’ve hit a rocky stretch because of their inability to have a baby after eight years of marriage. They decide that their last hope before divorce court is a week-long retreat at the Eden West Resort. And just in time.

Jason is so coolly analytical about everything that he even designs a PowerPoint presentation to show his friends the crisis his marriage is in, hoping that the other three couples will come along on the “couples retreat” as a package deal that will save him money.

But his friends are not as prepared to jet off to French Polynesia at a moment’s notice. Nevertheless, thoughts of all those palm trees and tropical fish are hard to resist, especially since Jason has downplayed the mandatory “couples skill building” sessions all of them are expected to participate in.

Vaughn and Malin Akerman are Dave and Ronnie, the seemingly happily married perfect couple, although their lives have become a multitasking hodgepodge of work and family projects that leave them little time for fun. Favreau and Kristin Davis are Joey and Lucy, high school sweethearts whose passion may have peaked. Shane (Faizon Love) and wife Jennifer (Tasha Smith) have recently split; he’s already trying to recover in the company of a precocious 20-year-old girlfriend, Trudy (Kali Hawk).

Couples Retreat promises a stew of simmering emotions that are only fitfully mined by the writers, who more often than not go for the easy gag, such as when a little boy decides to relieve himself in a toilet that sits in the middle of a home store’s showroom. Oof!

On the other hand there are generous laughs when the muscular yoga instructor Salvadore (Carlos Ponce) gets a little too touchy-feely while demonstrating some contortionist maneuvers or when self-help guru Marcel (Jean Reno) becomes a little too full of his mystical pronouncements.

There’s fun, too, in the silky voiced cool assessments delivered by the marriage therapists who manage to stir the waters in even the best of relationships. Amusing as this is, it may give some in the audience pause to question their own personal romantic equations.

Yet Couples Retreat isn’t meant to be too serious. Not when a massage session yields predictably amusing results, when Vaughn’s Dave faces ocean terrors or whenever the pompous resort manager Sctanley –– “with a C” –– (Peter Serafinowicz) reads the long list of rules that must not be broken.

Peter Billingsley, who was Ralphie in A Christmas Story a quarter century ago, directs breezily. It’s just the right touch for a film this light and frothy.

***Couples Retreat

Starring: Vince Vaughn, Jason Bateman, Malin Akerman, Jon Favreau, Faizon Love, Kristen Bell, Kristin Davis, Kali Hawk, Tasha Smith, Jean Reno, Carlos Ponce.

Rated: PG-13, contains sexual situations, profanity, violence.

mjanuson@projo.com