Is sex in Iain M Banks's Culture limited to orgies and one-night stands? The only romantic love I can think of is in the one that has a Hell and the one where they're descended from carnivores and they have a war that isn't their fault. But both of those are societies outside of the Culture. Can anyone think of examples within it?
In the back story to Excession, two characters - Dajeil and Genar-Hofoen - were a dedicated couple, going so far as to get one of them pregnant and then undergo sex changes and getting the other one pregnant too. The relationship only broke up when Genar-Hofoen was unfaithful.