Boyfriend won’t marry me

My boyfriend and I have been together for 6 years. He has known that I’ve wanted to get married since we got together. He was ambivalent and after two years of dating we broke up but not because of that. We were apart for only 6 months and we ended up getting back together. Things were better than before! He said he had a change of heart and was planning on us getting engage within 6months-1 year while he saved. It’s been 3 years since he said that. We are not engage and he now tells me he changed his mind. Again! I know marriage is not important to everyone but it is to me and he knows that. I’m just not sure what to do now.