Try this board - http://messageboards.ivillage.com/iv-rlclashing - populated by people with your same problem. One wants it "too much" another, "not enough."
It's only a problem that you two want different amounts. You shouldn't be forced to have it more to make him happy, any more than he should be forced to have it less.
If you two are determined to stay together, a compromise must be reached. You're probably never going to want sex as much as he does, you're not him. 3-4 times a week is quite a bit & if you keep having to force yourself into it, you'll resent him even more than you do now.
He can't be making all the decisions about how the sex goes either. If you don't like the way he touches you, either correct him or think up something else. What do YOU like? Be assertive with some of your preferences. No worrries about making him upset, because he already is.
Just because you've been together a long time, is really no reason to keep on with it. If a compromise can't be reached, there is no way to make you want it more or him want it less. You probably get different feelings out of the experience. You do it FOR him, he does it because he likes to do it.
Part of the problem could be that he can't, or won't, find fulfillment in other aspects of the relationship. Hugging & kissing, hand holding, walks in the neighborhood just to be doing something together could be ways for you two to be close without always having to get naked. A shared project, like remolding a room or a biking trip, whatever it is you two can enjoy together. You both can feel wanted & needed by the other without it always being sex.
There is nothing wrong with you. You don't need to increase your libido to his level, or it would be his libido & not yours.
Compromise & Communication!!!
Love 
