Part Two of the Something Wicked series  (S5, beginning with "Buffy vs Dracula")

Spuffy have been together for a while now.  Things have been great.  The Scoobies have more or less accepted the reality of their couplehood, Spike finally has his own place, so there’s plenty of thoroughly excellent shag-time, and college is kind of fun when you have a worldly, undead tutor to poke fun at your instructors and help you remember your lessons with fascinating anecdotes or, when that fails, incredibly memorable sexy-times.  Life is actually, like, bordering on good. 

But then Mr. Eurovamp 2000 blows into town and causes a bunch of jealousy.  And then Buffy starts having a bunch of crappy Slayer dreams about glowy purply stuff.  And Dawn is going off the hook even more than usual, and Mom is acting weird…  And, as if there’s not enough to deal with, Buffy’s pretty sure that idiot Riley Finn is still lurking around town trying to come up with a reason to shoot her boyfriend…

Buffy should have known things couldn’t stay yummy for long.  She probably would have started to worry if it had.