Ursula le Guin has a great selection of novellas in her book "The Birthday of the World and Other Short Stories." Especially the first short story.
Topics include asexuality, open relationships, bi, gay, straight, quad marriages, and she even invents a new word - "fuckery" - a place to go to get a good.. (more like a human studery, not a brothel as it's for both sexes).
Can I say fuckery here? oops.