Not legitimate government. Any person or persons with sufficient force can exert power over others, that is not legitimate government, it is power.
What about dowries or asking her father for her hand ?
Many groups of people belived in the ownership of other human beings. They therefore sold them and bought them. That is illegitimate power.
What about the duty of her kinsmen to kill you if you dishonered her and thereby destroyed her marital value ?
Slavery often inspires defending what the slave holder conciders property.
So you see marriage has always been backed up by coercive agencies.
Many bad things, including slavery, are backed by force.
It was never just two people saying they love each other.
Nonsense, people are married because of promises made to and before GOD. Not people with guns.
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.