It's key to talk about your expectations in general. Even if you shack up with the guy, let him know that marriage is ultimately what you desire. And kids if that's what you want.
You still might be dating a person that will yes you to death about it, but at least you put your expectations on the table, and he won't be surprised when you're out the door when he won't marry.
And yes, Lipp. I think that's ultimately what the vow is all about. A pledge to be with the person no matter what. For alot of couples, religious stuff aside, marriage is a way to deepen their bond.
“Inside every cynical person, there is a disappointed idealist”--George Carlin