J-Lo and Affleck tell their intimate secrets

Jennifer Lopez and Ben Affleck may be one of Hollywood's most glamorous couples, but the magic of their romance may not be enough to save them at the box office.

The stars have launched a publicity blitz centred around their private lives in an attempt to salvage Gigli, their first film together.

Critics are sharpening their pens in anticipation of a box office disaster to rival Madonna in Swept Away which was directed by her husband Guy Ritchie.

The release of the film has already been delayed for several months, with the name being changed to Tough Love at one point. Among late editing changes is said to be a decision to cut out references to Lopez's character being a lesbian.

Even a poster of Lopez for the film - for which both stars were each paid £8 million - was airbrushed at the last minute to reduce the size of the most famous bottom in showbusiness.

In an attempt to promote the film, the stars have agreed to open up their private lives as never before, with a series of television and magazine interviews.

The couple, who announced their engagement in November 2002, snuggled together for an interview on American television last night that showed J-Lo cooking in the kitchen and both stars insisting they were ordinary people in love.

Lopez, who ranks just below Affleck on the Forbes list of the world's richest celebrities, said of her lover: "He definitely wears the pants." The couple were interviewed at the lakeside home they have rented while both are filming on projects in Canada.

They also insisted their wedding - whose date and location is still secret - would be a simple family affair. Lopez, 32, even said: "If people want to stand outside and take photographs, that's okay with us."

Their relationship - dubbed "Beniffer" in the American press - is already being likened to the love affairs of previous Hollywood lovers Humphrey Bogart and Lauren Bacall and Katharine Hepburn and Spencer Tracy.

But the sexual chemistry of their private lives does not seem to have translated to the screen - much to the dismay of studio chiefs who had banked on a box office hit from their relationship when the film is released in the US later this month.

An early test screening of Gigli was seen by several reviewers for the Ain't It Cool website, run by film guru Harry Knowles who is credited with the power to make or break a film.

"Never have I seen such a disastrous film as this," was one verdict, while another reviewer declared Gigli "a film so bad, so god awful and so painful to sit through that I seriously think it's flat out unreleasable."

In the film Affleck, 30, plays a bungling gangster who kidnaps the mentally handicapped son of a lawyer, with Lopez as a rival hitman who falls in love with him.

In reality, Lopez was still married to second husband, dancer Cris Judd when she was making the film in 2001, saying that she was "just good friends" with Affleck at the time.

She tells the latest issue of Reader's Digest today that she is "a very faithful person, adding: "If someone had told me, 'Ben's attracted to you,' I would have said, 'No, I wasn't raised that way.'"

The actress and singer, who previously had a relationship with rapper Sean "P-Diddy" Combes, says that although she and Judd were having problems when she met Affleck on set, "to talk about that with another man wouldn't have been cool".

Lopez divorced Judd, her second husband, only three months before announcing her engagement to Affleck, who had a long affair with Gwyneth Paltrow. Lopez says she has set no wedding date and, after two failed marriages, is working hard at her new relationship.

"We talk about everything [with] brutal honesty ... And when you do that nothing's left to chance," she says.