The World Inside
The World Inside is a 1971 novel by Robert Silverberg.
Told from the perspective of a male character, the story explores the life of 24th century humans who live in giant, crowded skyscrapers. Because they live in such crowded circumstances, a ritual non-monogamous wife swapping is socially enforced--female consent has been criminalized, and all women are required to assent to sex when asked.
Other works:
- For the opposite take on crowding, jealousy, and monogamy, see --? novel in which human crowding in closed environment spaceships creates an elaborate regime of social levels for achieving intimacy; the male protagonist eventually leaves the spaceship with a woman who has unaccountably taken an interest in him, and they re-settle Earth.)
- For an even more nightmarish view of futuristic overcrowding in giant apartment buildings, see Sheri S. Tepper's novels Beauty and The Companions