Marriage is a team of two persons working together to preserve, enhance and fulfill the lives of two unique and equal standing persons.
Marriage has far more and much greater values than procreation. To restrict marriage to "between a man and a woman" is to diminish the value of marriage and the persons whose labor creates it. Children are much better served by fully developed parents working as a team.
The incessant push of religion to diminish marriage and persons and parents will continue to harm children and parents and persons by stigmatizing their family with the hypocrisy of others who wrongly devalue and decry them.
Their is no legal source of cause against same sex marriage. Only religion is pushing hard to diminish marriage and manipulation of the married, to gain access to more children.
The source article can be read here