I read a fic a long, long time ago where Anya had taken off on Xander, and he and Spike, who might have been living together, started fooling around. But then Anya comes back and wants to try again, and Xander goes with it. Only he still wants Spike. There was something about a concert and fooling around in a hotel room (I think after the big Xander/Anya reunion), and though I don't think that it was completed, the point I was at had Xander deciding that he wanted Spike, and that he was going to break things off with Anya. As I said I read it a long time ago, but any help in finding this would be much appreciated.