Buffy Viewing Update

So Spike and Buffy beat eachother up then have passionate sex while a building collapses on top of them. Kinky. What's interesting is this thing that now Spike can hurt Buffy even though his chip is working "perfectly." He says "you've come back wrong." Can this be true? Is it perhaps that she's gone against nature in coming back from whereever it was she was that she thought was heaven...? I love this show.