After two unimpressive outings with costume pictures based on classic literary sources, "The Marquise of O" and "Perceval," Eric Rohmer evidently decided to resume cultivating his own little garden of cinematic classicism. Once again he's specializing in a modest but distinctive way in the contemporary comedy of manners, with particular concentration on the nature of sexual attraction and desperation. However, he's also returned with a shift of sexual emphasis -- from the impulses of men to the impulses of women -- that goes peculiarly amiss in "Le Beau Mariage," which opened yesterday at the K-B Janus. Rohmer may or may not possess some insight into the psychology of women, but he seems to invalidate this character study by misplacing the heroine's appropriate chronological and mental age.

The earlier Rohmer features -- "My Night at Maud's," "Claire's Knee," "La Collectioneuse" and "Chloe' in the Afternoon" -- culminated a series he called "Six Moral Tales." (Two of the stories were filmed as dramatic shorts.) A heavily ironic title, "Le Beau Mariage" is the second installment in a new cycle-in-progress, "Comedies and Proverbs." The first installment, "The Aviator's Wife," hasn't arrived in Washington yet. Despite the repeated feminine ring of his titles, Rohmer had focused on the ambivalent, hypocritical behavior of sexually tempted but timorous men in the "Moral Tales." They were variations on the same premise, depicting the ways overcivilized men were impelled to behave in ordinary social and conversational situations when confronted with the fact of a powerful attraction to a newly encountered woman acquaintance. Typically, they drew closer to an open acknowledgment of their sexual interest, only to chicken out and run for cover in the last analysis.

Beatrice Romand, who plays the stubbornly wrongheaded heroine of "Le Beau Mariage," a young woman named Sabine, will be fondly remembered as the gawky teenage charmer of "Claire's Knee" -- the girl who didn't upset the protagonist with desire but did win the hearts of the audience. It's advisable to cherish those fond memories, because Romand's Sabine is not a happy invention as conceived or impersonated. It appears that Rohmer is on to something interesting at the outset, when Sabine is identified as a young woman at a turning point. Specifically, she decides that she wants a man of her own. This revelation occurs in the midst of a roll in the sack with her lover, a painter named Simon. Their exertions are interrupted by a phone call from Simon's kids, who live with his estranged wife. Suddenly, the priorities hit Sabine between the eyes. This just won't do. She needs and deserves a higher priority claim on the interest of the man she loves.

The upshot of her decision to break off with Simon and look for a more suitable consort is self-inflicted humiliation. Sabine embarks on an inept, embarrassing campaign of marital entrapment aimed at a prosperous, pleasant young attorney, Edmond (Andre' Dussollier in a very smooth performance), who simply doesn't share her intentions. Recklessly premature, Sabine goes around assuring friends, acquaintances and family members that a wedding is imminent when the object of her infatuation has responded to her overtures with politeness at best and is obviously trying to avoid entanglements and let her off as gently as possible.

The ruinous miscalculation in the story is Sabine's maddeningly juvenile approach to the man she wants. Although she's supposed to be 25, well-educated and sexually experienced, her behavior suggests a sudden regression to adolescence. She acts a great deal like Frankie Adams in Carson McCullers' "The Member of the Wedding," but the humor and pathos associated with Frankie's foolishness can't be generated for a young woman of Sabine's age and generation. You're simply baffled by her lack of smarts and sophistication at the game of romance, which you're led to believe she's been actively playing for some time.

"Le Beau Mariage" slips right through an unforeseen generation gap. Sabine's search for a husband can only make sense and inspire sympathetic interest if she follows through on the identity we're shown in the beginning. When she begins acting like a raw, ignorant ingenue, the whole movie loses credibility and pertinence, and they're never regained. The slip-up seems at once unfortunate and compulsive. Did Rohmer mix up Sabine with a younger character from an earlier draft or a totally different scenario? I guess it's back to the old drawing board, but I hope Rohmer does return to the same outline for a heroine, because it obviously would be fun to see what happens when modern, liberated girls like Sabine set their hearts and minds on marriage.