Starring Richard Gere, Diane Lane, Olivier Martinez, and Erik Per Sullivan, the film follows Edward (Gere) and Connie Sumner (Lane), a couple living in the suburbs of New York City whose marriage is jeopardized when the wife has an affair with a stranger (Martinez) she encounters by chance.

Unfaithful was theatrically released in the United States on May 10, 2002, and was screened at the 37th Karlovy Vary International Film Festival on July 8, 2002.

Connie falls into an escape fantasy that they could leave the country and assume new identities, and Edward agrees it sounds perfect.

According to actor Richard Gere, an early draft of the screenplay presented the Sumners as suffering from a dysfunctional sexual relationship, which gave Connie some justification for having an affair.

According to Gere and to director Adrian Lyne, the studio wanted to change the storyline so that the Sumners had a bad marriage with no sex, to create greater sympathy for Connie.

Both men opposed the change; Lyne in particular felt that the studio's suggestions would have robbed the film of any drama: "I wanted two people who were perfectly happy.

Once cast in the role, Martinez, with Lyne's approval, changed some of his dialogue and the scene in which he first seduces Lane's character, while she is looking at a book in Braille.

"[6] Lyne also wanted Gere and Lane to gain weight in order to portray the comfort of a middle-age couple.

After reading the script, Biziou felt that the story was appropriate for the classic 1.85:1 aspect ratio because it "so often has two characters working together in the frame".

Principal photography began in New York City on March 22, 2001 and wrapped on June 1, 2001 with Lyne shooting in continuity whenever possible.

During the windstorm sequence where Connie first meets Paul, it rained and Lyne used the overcast weather conditions for the street scenes.

The director also preferred shooting practical interiors on location so that the actors could "feel an intimate sense of belonging", Biziou recalls.

In a scene taking place in an office, the director pumped it full of smoke, an effect that "makes the colors less contrasty, more muted".

[2] According to Biziou, "The texture it gives helps differentiate and separate various density levels of darkness farther back in frame".

[2] The film has many explicit sex scenes, including a tryst in a restaurant bathroom and a passionate exchange in an apartment building hallway.

[2] To prepare for the initial love scene between Paul and Constance, Lyne had the actors watch clips from Fatal Attraction, Five Easy Pieces, and Last Tango in Paris.

[14] Unfaithful was released in 2,617 theaters in the United States on May 10, 2002, grossing US$14 million on its first weekend, with an average of $5,374 per screen, ranking in second place behind Spider-Man.

"[21] Entertainment Weekly critic Owen Gleiberman awarded the film an "A−" grade and praised Lane for delivering "the most urgent performance of her career", writing that she "is a revelation.

"[22] Roger Ebert of the Chicago Sun-Times wrote, "Instead of pumping up the plot with recycled manufactured thrills, it's content to contemplate two reasonably sane adults who get themselves into an almost insoluble dilemma.

"[23] Kenneth Turan of the Los Angeles Times wrote, "The only performer who manages to get inside her character is Lane.

Whether it's her initial half-distrustful tentativeness, her later sensual abandon or her never-ending ambivalence, Lane's Constance seems to be actually living the role in a way no one else matches, a way we can all connect to.

"[24] Stephen Holden in The New York Times praised the "taut, economical screenplay" that "digs into its characters' marrow (and into the perfectly selected details of domestic life) without wasting a word.

That screenplay helps to ground a film whose visual imagination hovers somewhere between soap opera and a portentous pop surrealism.

"[25] USA Today gave the film three-and-a-half out of four and Mike Clark wrote, "Diane Lane also reaches a new career plateau with her best performance since 1979's A Little Romance.

"[26] In his review for The Washington Post, Stephen Hunter wrote, "In the end, Unfaithful leaves you dispirited and grumpy: All that money spent, all that talent wasted, all that time gone forever, and for what?

"[27] David Ansen, in his review for Newsweek, wrote, "Unfaithful shows what a powerful, sexy, smart filmmaker Lyne can be.

"[28] Andrew Sarris, in his review for the New York Observer, wrote, "Ultimately Unfaithful is escapism in its purest form, and I am willing to experience it on that level, even though with all the unalloyed joy on display, there's almost no humor," and concluded that it was "one of the very few mainstream movies currently directed exclusively to grown-ups".