If trying to make Spike be the evil vampire again, they failed miserably.

I saw his actions as being totally in character and a logical extension of the mess that was their relationship. I saw Buffy as being as much at fault in the mess that was their relationship and her actions, especially in Dead Things, where she beat him unconscious and left him in the alley to possibly meet the sun.

She definitely had the power in that relationship and she abused it, several times, in several ways.