Roommates

At what point does a person decide that they don't want to live with roommates anymore? I realize that a lot of people don't like to live by themselves, and I also realize that some people enjoy the companionship. My question, however, revolves around a progression in life: grow up, become liberated from parents, get a place of your own, and live apart for your parents. Is there a point when you finally decide that you need to live on your own?

Is it always ok to keep looking for a roommate to stay with? I'm not trying to disparage the idea of living with roommates, I know it's a good idea economically, but is having a roommate something that's eventually "outgrown"? Living with roommates has always seemed, to me, that it goes along with not having any money; getting a roommate was a way of living without much money.

I guess I'm looking at it wrong; maybe a roommate is someone's way of getting out of not having companionship. Does there come a point when having a roommate is no longer feasible? Is it ok to be 40, single, and living with a roommate? The whole idea just seems a little out of order to me... but then again I've never had a problem living or staying by myself and I don't know what it would be like to not be comfortable living that way.