Not legitamite ? Are you saying that in traditional cultures people did not see family, tribe, church as legitamite government. Oh yes they most assuredly did. And it was always the function of government to protect and uphold marriage because it was the foundation of the family and the primary medium of welfare and property ownership. You had arranged marriages (and still do in many cultures) because it was far to serious a matter and far too important to society to be left to adolescent hormones.
Just as government law courts are the alternative to feud, duelling and vendetta, so government marriage is the alternative to arranged marriage, honor killing, the need for parental approval, fear of ostracism and all other coercive agencies by which societies have always forcibly upheld marriage.
Marriage has NEVER been between two individuals. The obligations are too heavy and it is too important.
Slavery is illegitimate, even if you embrace it.
You don't get to suspend my freedom because YOU have decided I can't make decisions for myself.
In case you haven't noticed, arranged marriages and the like are not allowed in our society.
PS, Hillary thinks government should make all these decisions too. She thinks we should all get permission from people with guns to do all kinds of things.