Marriage or Wedding, is the religious promise to sacrifice time, mind (freedom), and body for the purposes of creating amd nurturing children. Two individuals of opposite gender are bound Socially/Spiritually to work as one entity, mentally to be loving friends in nurturing the next generation, physically for the creation of the next generation(sex).
Marriage is NOT associating for Pleasure or Domination.
In Hinduism, "Fire" is God's witness and the medium of the promise. In Christianity, the "Jesus" is God's witness and the medium of the wow.
The original meaning of marriage as a spiritual union between a man and a woman, bound by laws of their religion, has been rewritten over and over by various institutions and governments.
Marriage was never meant to be a legal contract, thus no country's politics should have jurisdiction over it. Marriage rules should always be maintained by the religions, as it has been in the past.