I hear what you are saying. But, what rights exactly are taken away? And, how exactly do you define marriage in the law? What is your position on the polygamy debate and the incest debate? If you are saying that nobody has any right to tell you who you can or can’t marry, then it logically leads to discussing whether group marriage, polygamy, or even consensual incest relationships will be so recognized.
There has not been a civilization yet that has survived sexual licentiousness. Homosexual "marriage" is not the cause of the decline of Western civilization, but it is a symptom and in the big picture this will not end well. Marriage is about a lot more than who you like.