As said before, I don't think that marriage is necessarily failing, or flawed. I think humans are flawed, and bring their own flaws into the mix. And again, in most states it's not legal for my partner and I to be married. In our case, our relationships is not heteronormative to begin with, so there's little need (nor desire) to fit into that particular "box." Our household consists of three adults, and two kids. My partner, myself, and our (platonic) housemate, who is my partner's brother's ex, and her two kids (his niece and nephew.) A lot of love exchanged in all directions, though she's not the right flavor for either of us to click with sexually, all three of us share household responsibilities, bills, childcare, etc.

With regards to wiring... who knows? Some people derive a great deal of security from a lifestyle which is traditional to their culture, and find that it helps them know their place in the world. For some of us (me, haha) who are a little left of center in ALL aspects of life, that kind of thinking just isn't where I derive my sense of identity from. I define myself in sometimes a-traditional ways, but it's what works for me. Defining our relationship in a-traditional ways is what works for my partner and me (and my sub, and his sub, and our housemate...)