To add to that, I know of at least two instances of people in stable relationships with children who are not formally married (there's nothing really special about having a child with someone without being married legally speaking - the father signs a document stating that he's the father and is treated as such from then on; the mother is obviously known). That's really the kind of relationship I'd like to be in - one where you don't involve the state's laws in your close personal affairs. You can still have a ceremony and exchange rings, and the people I know do wear engagement rings.