gay marriage - where does it stop?

The definition of marriage, for I don't know how long, has been the union of one man, to one woman, to the exclusion of all others, for life.

Now if we entertain the idea that two men or two women can also get married, where is it going to stop?

Will marriage also include 2 women and 1 man, for example, or the other way round??

This is imo a legitimate question, because I don't see the progressives stopping with just this proposed change.

There will be more.

If I am ever given the chance, I will vote NO to any proposal to change the definition of marriage.