This was a deliberate thematic choice on Kubrick’s part, and a 2014 retrospective in Vanity Fair revealed that the director had a number of on-set rules to assure that Bill and Alice were consistently alienated from one another. Namely, Kubrick insisted that stars Cruise and Kidman — actually married at the time — remain apart as much as possible during the shoot.
According to critic Amy Nicholson, Kubrick directed Cruise and Kidman separately, giving them each their own notes that they were forbidden to share with the other. They were allowed to develop their own characters, but disallowed from comparing notes as a couple.
Additionally, Kubrick attempted to play with actual jealousy. In the film, Bill’s sexual odyssey begins when Alice admits to feeling marriage-ending lust for a soldier who just happened to pass by. Bill — and perhaps Alice too — begins having visions of Alice nude in bed with another man. In order to shoot these scenes, Kidman and a male model filmed naked for six days, posing in 50 unique sex positions … while Cruise was forbidden from visiting the set. Kidman was forbidden to tell Cruise about her experiences filming the sex scenes.
Cruise and Kidman are professionals, of course, and one might hope that jealousy would become a factor when one performs intimate scenes with another, but the terse nature of Kubrick’s movies likely still left a deliberately uncomfortable atmosphere. The shoot for “Eyes Wide Shut” was notoriously long, running consistently for 46 weeks, starting in November of 1996 and lasting until June of 1998. According to the Guinness Book of World Records, it is the longest consistent film shoot in cinema history.