Here we go...
The color theory in Eyes Wide Shut is meticulously executed and multi-layered. The use of rich red and blue is obvious upon first viewing to even the most casual observer. However, the meaning of these colors requires deeper analysis. Eyes Wide Shut is essentially the story of a man, Dr. Bill Harford, who is wrapped up in his own inner-world of lust and jealousy. He walks through life unaware of how lucky he is (having a beautiful and loyal wife, successful career, a healthy child, etc). He lives his life in a dream-like state with his Eyes Wide Shut, whereas his wife Alice seems to have an easier time distinguishing between reality and fantasy. This struggle between his compulsion to cheat and his loyalty to his wife is represented in the struggle between red and blue. Blue represents his wife Alice. Red represents his cheating impulse. Throughout the film we see red and blue choices presented to Bill. Below are a few blatant illustrations of this:
-The opening shots show Alice undressing facing a blue lit window with red curtains followed by Bill turning his back and walking away from the same windows and curtains. The following party scene at the Zeigler's (adorned with white and gold), has little to do with the blue and red motif but for two exceptions: Ziegler's wife is wearing a red dress and the drugged prostitute who sits on the red sofa chair (with the image of a nude woman on a red cushioned is mirrored in painting behind her). Also, note that once Bill recitates the woman he puts a blue blanket on her. He doesn't see her in a sexual way, but with concern for her well-being. This act of kindness later helps save him at the Somerton Mansion.
-The blue and red struggle essentially starts when Bill and Alice have their argument after smoking a joint. Alice lays on the red bed and Bill sits beside her, his head framed by the blue bathroom window. Once Alice starts telling Bill that she (and all women) have sexual desires outside of their relationships she leaves the bed and stands in the blue bathroom doorway then sits under the blue window. Bill moves to solely occupy the red bed. She then reveals her sexual fantasy of being with the sailor. Which throughout the film is represented as a blue vision in Bill's head. He fails to appreciate the fact that Alice was honest with him and ultimately loyal. Meanwhile Bill himself lies to Alice during the argument. The central conflict of the film is now set.*
-The argument is interrupted by a phone call from Marion Stephenson, whose father (a patient of Bill's) has just died. He rushes to her apartment. Once there, Marion comes on to Bill. The lighting on Marion's face make her look awful and her dead father is right between them. Bill has no interest in this woman and her apartment is devoid of either red or blue. With this woman, no conflict within Bill exists.
-After leaving Marion's apartment, Bill is walking down the street lost in jealous (blue) thoughts of Alice and the Sailor, when he is suddenly attacked by the obnoxious gang of guys (all wearing Yale shirts i.e. Skull and Bones) on the street and is shoved against a bright blue car parked in front of a bright red car. He stands next to the red car as the group belittles him and hurls homosexual slurs at him. Now angry and jealous, with his manhood questioned Bill continues down the street.
-The following tracking shot of Bill walking down the street is bombarded with blue and red passing before him, canceling each other out. He is conflicted. Note, that Bill walks by a bright blue door. While waiting to cross the street, a neon sign in the background reads XXX VIDEO. It is at the exact moment when Bill's head is directly under the red XXX that the prostitute (named Domino) approaches him. They walk just a bit further as she solicits him. They stand in front of her apartment building which is (of course) adorned with a big bright red door. He goes in with her.
-In the apartment Bill and Domino begin to kiss. Their profiles fill the frame with the exception of two little Christmas lights. One blue, one red. The kissing is interrupted by Alice calling Bill's cell phone wondering when he's coming home. Her cutaway shot is bathed in blue. Bill ends the encounter and leaves...