Sorry to be a film dullard, but what was that bit of sexual nihilism from?
The premise in
Logan's Run is that there is a perfect society in the future, everyone is beautiful, plenty of everything (incl. sex) for everyone, etc. The catch is after you turn 30 you have to go someplace else, and it turns out that someplace else is actually the morgue. Kind of like the recent flick
The Island, except without the cloning/organ donor aspect.