Listen to what you are saying:
You are going to break off a perfectly successful relationship just because he hasn't bought you a ring?
Silly and childish.
In a significant other, you should be looking for, amongst other things, prudence.....seems as though your guy is practicing this.
Furthermore - If you are familiar with laws these days, you'd see that there is little to no incentive for a man to legally married.
Just because our culture preaches it, marriage is not something that you rush into. Kudos to your man for not doing so.