My God, Gwyneth Paltrow is thin. The poor, poor woman. She appears to be made out of clothes hangers twisted into the shape of a cocktail waitress. It ain’t healthy. If she ate a peanut, you could watch it move through her body like a mouse inside a snake. Her shoulders couldn’t support the weight of those pads they put inside some dresses. She could be the anti-Santa Claus — easily sliding down all those modern 6-inch chimneys to deliver bottled water, individually wrapped salads and jars of Dexatrim tablets to all the good little boys and girls. You’ll have plenty of time to think up your own hilarious ain’t-Gwyn-thin banter during the course of Bounce, an idiosyncratic but depressingly weeperific romance made for Miramax Pictures by writer-director Don Roos and starring that studio’s royal couple: Paltrow and Ben Affleck. Concern for Gwyneth’s health could be the primary thing that sticks with you from this picture, which flails admirably against the banal conventions of its underlying story, but eventually falters. Affleck plays Buddy, a hot-shot advertising executive who gives up his seat on a plane to Greg (Tony Goldwyn), a guy he’s never met, so that he can remain landlocked to score with a babe (Natasha Henstridge). The plane crashes, and Buddy’s high-flying world plummets with it. Convinced he killed Greg, Buddy drinks a metric ton of booze before joining AA and setting out to make the requisite amends, including a visit to Greg’s widow (Paltrow) to offer financial assistance. Sparks are supposed to fly, but never really do. Roos writes some excellent scenes between the leads, but neither of them is particularly convincing as a put-upon soul struggling against a nasty turn of fate. It might be the fact that Ben and Gwynnie are both really big stars, rendering it difficult for an audience to accept that these two incredibly lucky people have ever lost anything more important than the second set of keys to the boathouse in the Hamptons. Affleck’s roots as an actor will always be grounded in the Kevin Smith school of a**hole cynicism, so he’s tough to believe in earnest roles. You keep expecting him to roll his eyes at the camera when Gwyneth isn’t looking. And then there’s Gwynnie, who dyed her hair brown for the role because she apparently thought that would make her look more like a housewife. The trouble is, she looks like a housewife on a hunger strike against people who wear white after Labor Day. In other words, she looks and feels like a movie star, not a heartbroken single mother. Both stars are great at reading lines, but that’s all they are: stars reading lines. The ineffable acting transformation just doesn’t take place. As in Roos’ directorial debut — the mean, bitter and gloriously funny The Opposite of Sex — Bounce contains long, wordy scenes that should elicit complex character building. He also loves small touches of detail that convey personality in ways words, and his actors, can’t. But despite Roos’ yeomanlike attempts to somehow bend and stretch a standard melodrama into new and interesting knots, we can’t shake the feeling we’ve seen all this before, only in less fancy trimmings. Stripped of Roos’ clever contrivances and the two megastars’ relationship-within-a-relationship intrigue, this is simply a star-crossed romance that travels a well-worn path. Bounce keeps us slightly interested, but it doesn’t keep us guessing.