Mine was similar, even if we ended up engaged lately. But even then I felt he always was one foot out the door. Perhaps they intuitively at least know how they are not ready for mature relationship, so that is why they behave like that. But maybe its a good thing actually- at least he didnt lure you into marriage and promise you I dont know what!
I am doing NC with mine now and having hard times with picking up the pieces of the lost dream. But I guess it WAS only a dream to begin with. As any sickness needs to be dealt with first in order to move on in life with more fulfilling stuff, like being in a relationship etc.