Director Adrian Lyne (Lolita, Indecent Proposal) has a thing for issues of fidelity and relationships. Movies like Indecent Proposal and Fatal Attraction demonstrate Lyne wants to explore issues regarding trust, and Unfaithful is no different. Here, Lyne wants to look at the effects of an affair on both partners of a marriage. Superficially, Edward (Richard Gere, The Mothman Prophecies, Dr. T & the Women) and Connie Sumner (Diane Lane, The Glass House, Hardball) have a good marriage. They have a young son (Erik Per Sullivan, Wendigo, Joe Dirt), a nice house, Edward owns a business, and Connie participates in community functions. On a deeper level, the love between the two is gone. They are friends, but it's hard to say whether or not they are in love. Unfaithful is based on the 1969 French film La Femme Infidele.

The slump in their relationship comes to a head on a windy day in New York. Connie literally runs into Paul Martel (Olivier Martinez, Bullfighter, Before Night Falls), a sexy young book dealer. She skins her knee, and Paul invites her up to his apartment for a Band-Aid. Paul represents things that her husband does not. He is spontaneous, lively, and extremely attentive towards Connie. He also obviously has his sights set on seducing Connie. He turns into an obsession for Connie, who begins a steamy affair. All the while, Edward suspects nothing. Unfaithful unfolds in three main acts. In the first, Connie deals with her own emotions towards infidelity. The second is the affair, and the third is the ramifications when Edward discovers what is happening.

The best scenes involve Lane. The screenplay by Alvin Sargent (Anywhere But Here, Bogus) and William Broyles, Jr. (Planet of the Apes, Cast Away) gives Lane ample opportunity to express a wide variety of emotions. She ably expresses the hesitation and near revulsion of a potential affair, the bliss of hedonistic pleasure, and the realization that what she is doing is horribly wrong. Lane is one of the better actresses working today, and for whatever reason, most people still don't know her. The emotions she expresses when she finally gives in to Paul's advances are heartbreaking. She is happy and horrified at the same time. Gere and Martinez pale in comparison to her. Their characters are shallowly written and devoid of personality. This may be what they intended for Edward, but he undergoes a personality change in the last portions of the film that do not make sense. Martinez needs to do nothing more than walk around with his shirt off.

Unfaithful falls apart in the third act. Lyne defenestrates everything he carefully constructed with a ludicrous action by one of the main characters. Lyne wants the viewer to relate to the introspection that each character is undergoing, and to realize how difficult the choices they need to make are. However, the events play off as unintentionally funny. This is partially because of Gere's approach to Edward, which is mostly hands-off. The denouement also takes much too long, forcing the viewer to watch while Lyne tries to convey his message. Lyne shot two endings, and used the first, which is more ambiguous. This is more realistic and brings the level of Unfaithful up a notch, but comes a little too late.