It starts off with Spike giving Xander a blowjob against the wall, then jumps ahead a little in time. Spike and Xander are in a relationship (duh) but Spike has kept them a secret from the rest of the group. Xander gets fed up (Spikes only given him one blowjob and never let Xander top) and kicks Spike out. I think Spike made hasty reparations and was allowed back in bed and Xander made a verbal list of complaints. Spike honestly feels bad and gives Xander bucket loads of pleasure in bed that night but the morning after (he's not a morning vampire) he makes, what Xander perceives to be, an insult towards the list. Xander says that Spike hasn't changed and kicks him out again. Spike, realizing that the only way to get Xander back was to find out what had gone wrong thus goes running to Giles where he suddenly remembers all the bullets on the list (one of which was that Xander does not fancy Giles as he's a father figure).
I'm also pretty sure the story was three chapters long on Spanderfiles. Does anyone know of this story??? Please, please?!?!?!?!?!!?!