Not "he should stay single" - I loved him with Anya, and I've also been warming up recently to the idea of him and Faith going full circle by eventually having a relationship. But Xander and Buffy doesn't work at all. She sees him like a brother.

The minute he left Anya at the alter he was dead to me.

True dat!

He'd have been better than Spike for sure. Unfortunately, she was never actually attracted to him.