Marriage CAN ONLY BE, between one man and one woman. What in that truth is so difficult to digest, understand or accept?
Why? Because it is the truth, and because it is the way we've all been created. No, we are not the consequence of some 'accident' that generated men and women at random in random relationships.
God, our creator, the one and only living God, has made us to His image and likeness, giving us the dignity to be free under His law.
Humans do not make the law, God does and any law, humans dictate which do not agree with the law of God become an abomination.