When Spike returns home early from a gathering he sees something that causes him to go running from their little home...the sight of Twilight and Caramel together.
Once Twilight finds him, shivering and cold, she decides to try to address his fears...by giving him The Talk.
But, to Twilight's surprise, it may not be a talk about basic biology that Spike needs...perhaps something far more important is on his mind.