Let us be honest with each other. The threat to marriage is not the gays. It is a lack of loving commitment - whether it is found in the form of neglect indifference cruelty or adultery to name just a few manifestations of the loveless desert in which too many marriages come to grief.
Traditional marriage between a man and a woman has been a cornerstone of our society for generations. If we are going to change that it ought to be done by the will of the people.