Carrying an off-screen persona into movies often works, of course. It does for Mr. Vaughn, whose regular-guy routine, the working-class demeanor and untoned bod, suits his "Break-Up" role. But even if we assume that the characters' romance was an upscale-downscale attraction of opposites, Ms. Aniston's gleaming self-assurance in the film is intrusive. After the breakup and a supposedly excruciating night, she arrives at the art gallery where she works and is told by her style-conscious boss (Judy Davis) to go home because she looks terrible. Except she doesn't look anything like terrible; she just has her hair pulled back in a very chic ponytail.

And in the long run, all that coyness about her possible relationship with Mr. Vaughn may turn out to be a misbegotten strategy, echoing the coolness and emotional reserve of her characters. Maybe she does want to keep her private life private, but the evasions have simply ginned up curiosity, which isn't the same as affection. Audiences like to feel a warm connection to their movie stars, like Tom Hanks or Julia Roberts. It's an illusion, but a comforting one.

The relationship with Mr. Vaughn itself may have cost Ms. Aniston sympathy. In terms of her image it doesn't even matter if that relationship exists; the public believes it does. And while replacing Mr. Pitt with a new trophy guy would have seemed like vindication for the wounded princess, instead she has reached beneath her on the celebrity food chain. Mr. Vaughn seems smarter than his on-screen persona, and his mega-hit "Wedding Crashers" gave him some Hollywood clout. Still, nobody says, How did she get him? Just the opposite.

To have a (possible) private relationship dissected so brutally by the public seems unfair, but then every star is complicit in constructing a public image. Some are just better at it than others. So, with her misguided media strategy, Ms. Aniston gives television interviews about the yummy hot dogs in Chicago, where "The Break-Up" was shot (and which, she doesn't add but people know, is Mr. Vaughn's hometown). The audience sees that she has not turned a frog into a prince; she has joined him down on the lily pad. Meanwhile, Brad Pitt and Angelina Jolie, perfecting their mastery of the media, have gone from adopting children to adopting a whole country, Namibia. Remarkably, the press has swooned for this stunt, recasting the cad and the femme fatale as humanitarians instead of two people who brought along their Los Angeles obstetrician and who knows how many other loyal retainers to Africa to stage-manage their baby's birth.

No actor who made $18.5 million last year, as Ms. Aniston reportedly did, can be called a failure. But her biggest box-office success, "Bruce Almighty," the movie that gives Jim Carrey God-like powers, wasn't really her film; "The Break-Up" belongs to the two-headed Vaughn-Aniston box-office anomaly. "The Good Girl" was hers. As an unhappily married woman who works at a discount store and is attracted to a younger man, she did more than pull her hair back; she disappeared into the role and made that woman understandable, believable and moving. "The Break-Up" won't be her last chance to create such a commanding presence, but it doesn't help, and it leaves fans of her real acting talent with a whole new Team Aniston goal to root for.