I have spent the better part of a week looking for this fic and I can't find it.
Basically Xander and Spike are together and for some reason Xander ends up being turned and now does not think Spike loves him anymore, Spike also acts distant from Xander. I think Angel was the one to tell them to pull their heads out. Xander thought the Spike just plain did not like him and Spike looked at vamp!xander and sees his mistake or something about turning him. Angel tells Spike that vamp!xander and human!xander are one and the same and to stop pushing him away.
I know not alot to go on but hopefully someone can help me, about the only vamp!xander fanfics I like!
Found by drangonfly_64
The Offering by spikedluv