From Phyllis Rose's Parallel Lives: Five Victorian Marriages:
Marriages go bad not when love fades — love can modulate into affection without driving two people apart — but when this understanding about the balance of power breaks down, when the weaker member feels exploited or the stronger feels unrewarded for his or her strength.
People who find this a chilling way to talk about one of our most treasured human bonds will object that “power struggle” is a failed circumstance into which relationships fall when love fails. (For some people it is impossible to discern the word power without adding the word struggle.) I would counter by pointing out the human tendency to invoke love at moments when we want to disguise transactions involving power.
Via DragonladyFlame, who quotes the book at much greater length.