As someone who knows what its like trying to make a relationship work with someone who is prefect apart from his habit of "communicating" like a clam...

You have to talk to him, and you have to do it at a time when you are calm, in a non-threatening way and without other things getting in the way. You have to tell him how you feel about him, what your needs are and how his "mental block" is effecting you. Write it down in a letter, if that makes it easier and either mail or read it to him. Make it clear that you care about him and that you want to make this work, but that he has to make an effort to work through it too. He has to tell you the reason and it would be good if you could get him to talk to a kink friendly psychologist. If he truly cares about you he should make the effort.

I honestly hope this works out for you both.