I was with my sons dad for 11 years. In the beginning I wanted to get married one day, but he had made it clear that marriage to him, was just a piece of paper. He didn't want to get married. I think marriage to me is important because I feel it is an expression of your love for one another and it cements things, because I'd only want to get married once, to someone who I truly love.
We never did get married and we did eventually split. Not because of the differences of opinion but because we just weren't working.
I met my husband in 2010 and we got married just under a year later.
I don't think marriage is for everyone, and many will stay with someone happily throughout their life and not have to get married. But if its important to you, for whatever reasons you have, is it worth telling him how you feel on the subject?