I wonder why you're with him, if you're not turned on by him? Is he some rich kid that you HAVE to be with? Or an alpha male of sorts in his group? You sound like you're in a high-school bullshit situation such as a who's whose crapola.
The other option is that you enjoy him for his kind and personality, but not the sex, but i don't suppose that that's the case, i opt for the previous theory above.