Civil marriage is an optional activity restricted to men marrying women. My penis, I'm pleased to say, has not played a role in my step-parenting. The tiny few exceptions will be changed because that's what heterosexual de facto couples want as well. Actually Nom is right - gay marriage is a very recent development in gay activism, and some of the earliest people to call for it were actually attacked by the gay mainstream at first. Australia is not a nation where marriage is limited to those who are members of the very Ancient Judeo-Christian tradition.
Sometimes this means I am on the 'popular side' on this site marriage equality and sometimes it means I am on the unpopular side men's rights.
Remember this? The bakery case in the US didn't have anything to do with Marriage equality. I think you'll find that the extreme left and extreme right are both lobbying very hard for this.
Dull is the only conclusion I can make.