I was in the exact same situation 2 weeks ago. We'd been together 11 years, I wanted to get married, he wanted me to move in (but had only ever mentioned it casually). He started talking about how marriage was such a huge step and he too was from a family rife with divorce. I was prepared to compromise by staying with him on occassions, when I suggested this...he broke up with me.
My instinct is now that if someone doesn't know if they want to marry you after that length of time, they're never going to marry you. I'm sorry to say.