I can really sympathize with you, but unfortunately I have no words of advice. Bur keep at it, because when it does happen it will matter that much more. I waited 22 years for him to ask. He always told he would but there was always a reason for delay. I am not 100% sure what made him do it now but he did. I had lost all hope of him ever asking. I figured maybe I was wanting to much and should just find a way to be happy. But it came up all the time, and just before Christmas he asked! He told he was nervous and unsure of how to ask! Like he had anything to worry about after 22 years and 2 kids. Yup, thats me wait all these years for the Big Question, so I could say no and walk away! But I guess thats a man for you.
Good Luck I hope you can find a way to make him understand, because if it was just a piece of paper, you could get a blank photocopy and fill it in yourself. But it is the meaning behind the paper, what all the hoopla is all about. It is not just a piece of paper but a way to shout to the world that you belong to each other and love each other above all. That you are and always will be the most important person in his life.