That's what Paula asked me today :lol: We're both in our late-20's...single (well, me still, technically) and never been close to getting married. We both had long-term boyfriends where we talked about being married...but there was never any planning or engagements.
I think my answer was "I don't know."
Right now, I don't have an urge to be married. Even as a kid, my plan for marriage was to hit 30, first. I'd like to be. I talked to a life coach once. She said, "if you want something to happen, you have explicitly express it. And be specific."
Maybe it's how I've grown up...and the messages I've received [yes, yes! Blame the media!!]. I dunno. Most of my friends are around my age are not married. I would like to be, though.