Waters might like to consult Article 16 (1) of the Universal Declaration of Human Rights.
It is, of course, true that many people never get married, but this no more shows that there is no human right to marry than the fact of there being large numbers of atheists shows there is no freedom of worship. The right to marry is not a claim right - such that you can insist on someone somewhere being obliged to marry you. But it is a liberty right; it entitles adults to get married if they can find willing partners. Gays are today claiming this right, and to deny its very existence is as feeble a form of opposition to their claim as you'll find.