I will give you one reason for government recognition of same sex reltionships. I lived abroad for work for several yers . A good American friend of mine - a salt of the earth Midwesterner - lived abroad as well. This friend has a non American same sex partner. They have enjoyed a monogamous relationship for 15 years now. My friend would like to return to the US to be closer to his parents as they age. But my friend's foreign born partner cannot get legal residence in the US. If my friend had an opposite sex partner, this would not be an issue. So there is a case of blatant discrimination. Eradicating this discrimination would not in any way harm what the author calls "natural marriage".