The Power of Love" is simple extreme devotion towards a goal or person. Other emotions, such as hatred, would grant the same magnitude of power.
The Power of Hate. (Hate is the Strongest Force in the Universe.) The hero's overwhelming hatred for the villain and all the horrible things he's done sees him through all his trials just so he can take that son of a bitch down hard.
1. The hero makes a stirring speech about how his love will prevail over all, but when it gets to the fight, the villain beats him handily. As the hero lies dying on the floor, the Mooks lead his love away to be executed.