Have you read
West of the Moon, East of the Sun by Knifeedge?
I keep having the strangest dream. Every night it's the same thing: a dark room, a big bed, and a silent vampire that I can feel, but not see. I'd be wigged, except it's just a dream, right? It'll be a cold day in hell before I ever willingly sleep with a vampire again...
No one gets into Spike's head like KE does. She writes both Buffy and Spike true to charector. In my opinion this would've been a better season 5 then the one we got. I know you wanted something later on but this was the only one that came to mind.
Cast Me Not Away by Enigmaticblue A long series exploring the ramifications of love, loss, and belonging. Spike leaves after "Dead Things," wanting nothing more than to get Buffy out of his head. Wesley's still an independent contractor after the events of "Loyalty." And Buffy's still living in the land of denial.