I will agree that it sounds like he just might not have it in him to be as punishing as you want. Have you tried letting him read stories that you write? Maybe that will give him a more "graphic" and "in your face" representation of what you want.

I am very in love with my partner and would never do anything to hurt her that she didn't want...but at the same time I don't mind beating the piss out of her if it turns her on!