“Every time you show up like this, you risk all of your parts, you know that?” Buffy says. “I wouldn’t be here if I didn’t have a good reason,” Spike replies. Of course Spike had a good reason. Lots of good reasons. All kinds of them.
Season Five, missing late night NO THEY WERE NOT DATES! from between Fool For Love until before Crush.

In this Season Six story, Buffy and Spike did not come to grief in Seeing Red and so Spike didn't travel to Africa, but Tara did die and Willow did go to the dark side.
But she has now gone to England to recover and Buffy and Spike have been left to sort out Tara's possessions. What they find will send them on an extraordinary journey.