That's a nice theory of life . . . but legally irrelevant.We both already know that it's not a theory. It's a practice, a longstanding historical practice with precedence.
You ask why special legal treatment is given to married couples, and I'll tell you that it is less related to religion and various worldview traditions than it is to economics. We can debate this point if you want to, but I think this is something we agree on.
Looking at the Griswold case, I do agree with the courts regarding marital privacy, but I leave open the question of the rights of the father in terms of co-equal creation of a new life resulting in pregnancy. In simple ethics, it takes two to create one, and these two share equal decision-making responsibilty.