Too often movies portray adultery without portraying the consequences. Not so in Faithless. The entire movie is a flashback as told by Marianne (Lena Endre, Gossip, The Eye) to Ingmar (Erland Josephson, Light Keeps Me Company). The name Ingmar is important for a couple reasons. His true identity becomes clear near the end of the film. The name 'Ingmar' is never mentioned, it only appears in the credits. Ingmar Bergman (Private Confessions, In the Presence of a Clown) is also the author. Faithless is based on the break-up of his parent's marriage, and is directed by Liv Ullman (Lumiere and Company, Private Confessions), Bergman's frequent collaborator and ex-wife. This information gives an intensely personal feeling to the film.

Because Marianne is reminiscing, she is able to look at events with a little more objectivity. She can analyze her actions and the actions of the people around her, and realize where she made mistakes. The movie does not go into too many particulars about her marriage to Markus (Thomas Hanzon, Breaking Out); instead it begins around the time her affair begins. David (Krister Henriksson, Juliane) is a friend of both Markus and Marianne, and the offer to sleep together seemingly comes out of nowhere. Soon, Marianne and David plan a trip to Paris while Markus is touring in the United States. All hell breaks loose when Markus discovers the affair, and this is where much of the emotion enters.

Ullman lets the drama build step by step by frequently coming back to Marianne telling her story to Ingmar. She also allows Marianne to speak at length about her feelings. The viewer has a good sense of what she is going through, and all her thoughts. Endre fully inhabits the role of Marianne, putting emotion and candor into her performance. She lays bare her deepest thoughts to Ingmar, allowing him and the audience to glimpse through her thought processes. Ullman also takes the time to show what happens after, to both Marianne and the people around her. The affair virtually destroys her family life. At times, it seems that not much is happening in Faithless, which is true to a point. Much of the story comes out in conversation and ruminations. Faithless is much more thoughtful than other movies in this sense.