WHEN A MOVIE starts with someone staring into the camera documentary-style and directly addressing the audience, drop those Jujubes and run back to the box office. There's still time to get your money back.

Nine times out of 10, the movie will never recover. How could it when the characters are already forced to explain everything?

"The Story of Us," which amounts to director Rob Reiner's mistaken impression that he can duplicate "When Harry Met Sally" with a bad script and Bruce Willis and Michelle Pfeiffer in the leads, doesn't just fall into this awful category. It plummets there.

Actually, Willis and Pfeiffer take turns staring into the lens and talking to us about their failing marriage. Imagine two deer in the headlights, trying to be funny. Clearly, Reiner enjoyed the dueling, psychoanalytical confessions of Diane Keaton and Woody Allen in "Annie Hall." So he appropriated them.

But he forgot to tell writers Alan Zweibel and Jessie Nelson to make the scene, uh, funny. We're left to cringe with embarrassment at the performers' weak attempts to get through their scenes alive, as if a dinner guest has started a long-winded joke that we know can only end badly.

Willis is Ben Jordan, a writer who doesn't pay attention to the finer points of preserving a marriage or parenting. Pfeiffer is his wife, Katie, a crossword puzzle designer who only pays attention to the finer points. She's the self-labeled "designated driver" of the relationship.

After 15 years of marriage, they agree to a trial separation. They dispatch 12-year-old Josh (Jake Sandvig) and 10-year-old Erin (Colleen Rennison) to summer camp, then begin the tough business of living apart.

What, exactly, is the source of the Jordans' marital discontent? "Life itself" seems to be part of the answer, judging by the highlights reel of yelling matches from the past that repeats itself throughout the movie.

The rest is all he said-she said hokum. Ben is apparently one of those guys -- defensive, prone to affairs, uncommunicative. Katie seems to be one of those gals -- accusatory, whiny and uninterested in sex after children. Maybe, deep down, they're angry about being one-dimensional. It's no picnic to look in the mirror and see a cardboard cutout.

There's only one thing worse than the bad side of the Jordans' marriage: the good side. I refer to those "cute and funny" sections, where Willis and Pfeiffer make beautiful music together.

When they first meet, for instance, a bored young Ben (wearing a bad toupee even then) throws paper clips at Katie, who's busy trying to type. She seems to ignore the projectiles falling around her. Finally, when he throws a handful of clips, she gets up, walks away, then reappears wearing a pith helmet with a flashing light. Hey, nothing but laughs between these two.

Speaking of hilarity, every romantic comedy has its comic-relief players. And you haven't lived until you've met this bunch. How about Ben and Katie's four parents (including Red Buttons and Jayne Meadows) who make a surrealistic appearance in their adult children's bed one day? Or Stan (Reiner) and Rachel (Rita Wilson), the Jordans' best friends who pepper everything with thud-heavy commentary? I'm still trying to understand Stan's metaphor about relationships and derrieres -- something about your behind being an extension of your thighs. If anyone actually watches this film, perhaps they could help me out. And then there's the great low point in the movie, when Rachel attempts to better the Meg Ryan orgasm scene in "When Harry Met Sally" with a prolonged monologue in a restaurant about male and female genitalia. At that point, you're more than ready for the check.

THE STORY OF US (PG-13, 96 minutes) -- Contains obscenity, sexual situations and "comedy." Area theaters.