Replacing a man's female partner with a male partner.
I always thought this was a rather poignant event in this film.
LUH 3417 is a woman of course, and she is paired by the state with the male roommate Robert Duvall THX 1138.
The pairing seems to show the expectation by the state that a sexual relationship might develop.
Once the pair are suspected of anti-state thinking, LUH 3417 is removed from their apartment and replaced with Donald Pleasence as SEN 5241.
THX 1138 is aghast. This is complicated by the fact that SEN 5241 is homosexual and expects sex from THX 1138. Hahaha.
This dystopian concept that sexual orientation is irrelevant, and the state just expects you to get with anybody, sends an interesting message.
Discuss.