This can happen with any antidepressant. Or not. Just depends on the person. Only thing I can recommend is if you decide you don't want to stay on this drug, stop it sooner rather than later -- it's a very difficult one to stop taking when you've been on it a while. As for this feeling, it could pass or it could last. I think you having the desire is a good thing, many people lose that as well, but difficulty enjoying the act is one of the most common antidepressant side effects.
I had similar problem & my support group put the blame on the Cymbalta.
Some people say Wellbutrin has less sexual side effects.