He sometimes wonders if his soul has a happiness-clause just like Angel's. Not the kind that will make him lose it at the moment of perfect happiness, but rather a cosmic rule written down somewhere saying "Spike must never be truly happy" as if the future of the world depended on his misery, requiring that whenever there is a even the slightest chance of him being happy, the Powers must intervene with a divine kick in the head.
Or perhaps his soul really is like Angel's, and the Powers are just making sure he doesn't lose it. Because he's a sodding champion now, isn't he.
He likes to think that it's like karma, likes to pretend that all those things happen because it was fated, because he's a part of some grand cosmic plan. Likes to pretend that he isn't quite capable of screwing things up himself.
But he has never been a good liar, not even to himself, and there was more than one reason why the night in the abandoned house with Buffy terrified him.
And so when they stand on the edge of the apocalypse and she finally sees him, finally says those three words that still mean more to him than he would like to admit, there really is just one thing he can say.
"No, you don't. But thanks for saying it."
She leaves, he stays, and the world keeps on turning.