Hi inkblot,
I'm not sure if you have or not, but try explaining your situtation to this guy. Also, tell him that you need lots of time.. and there are a lot of people that wait until they are married anyway. It can be hard on a relationship anyway for people to get that close, but not be 100% commited yet. There is always this thought of oh i might lose him and look at what i'll be losing with him. Although, this is just in my opinion it might be different for you, but you might want to explain that to him.
-Audrey