Spike didn't know anything about what happened between she and John Winchester. He imagined that the daughter thing had a lot to do with the amnesia rubbish that had been forced upon them all before, at least. Spike was able to understand suffering from the feelings that something like that would be able to cause. After all, Spike was still unreasonably disappointed about not being able to rescue that old lady with the cane.
"There's a future out there," Spike started, "one in a million. A bazillion, even. And it's got you and him being decent to each other, is that it? What about the other futures where you could destroy him or he could destroy you or you could destroy yourself? 'Cause, really, it's looking loads hopeless right about now and I'm trying to do you a real favor by telling you to step away from it all now." Spike couldn't convince her of it, he was sure. He had seen the look in her eye already. It wasn't exactly the same as the one that he'd had when he was trying to prove himself to Buffy, but it was familiar.
It was also incredibly stupid.
He took the herbs from her and stuffed them into his pocket. Good thing about a big old jacket like this one? It had plenty of room for carrying junk around. When he was good and finished, Spike leaned against the counter and nodded. "Yeah, I want you to close up shop and come with me. You staying round here hating yourself? It's unhealthy. Let's go kill something."