But once upon a time, marriage served a function. The marriage of two people, a man and a woman, was not merely the joining of two people in love to support each other through good and bad; marriage served the society. A man and a woman in marriage love each other and procreate. New children, new members of society, new citizens are born and raised in this construct, taught and trained and nurtured for adult life. And that is why the government has a duty to protect and support the family structure - it is good for society and builds society.
My stance is not going to be popular but I know this is true: children need a mother and a father. That is true biologically and it is true psychologically. Children can survive without one or even both of their parents, but it is more difficult for them. For example, young boys often suffer, these days, because of the absence of a father. Sometimes another male father-figure in their life helps them stay on the path, but studies have shown that children usually do better with both their parents.
Of course, that is ideal. Sometimes, that can't always be. But a homosexual union fails to fulfill the goals of marriage completely. They cannot procreate children, and children they raise have two of one gender and are denied their need for the other. Furthermore, a man or a woman is used to create a child on demand and then never participates in the life of that child again. Their motherhood or fatherhood of the child is denied. The child grows up not knowing who they came from, their background, or their origins. They don't know who they are. They don't have roots. This will sound harsh, but the biological parent essentially seems to say, from the perspective of the child's heart, "I don't love you. You were created for the pleasure of your homosexual guardians. Have fun with your life." Even adopted children have to deal with that phenomenon, never mind a child brought into the world through a surrogate mother.
If you are homosexual and want to live with your significant other, I can't stop you. But you don't need marriage. Marriage serves to create and bring up new people in a stable home, ideally, with both a mother and a father. Science has shown, testimonies have shown that children need that. [And yes, that affects how I feel about divorce as well.]
And society suffers if it defines marriage as whatever you want it to be. Because the children suffer.
I'm not anti-love. I'm pro-marriage.