I am familiar with the people who live on our little cul de sac, that's how I know.
But how do you know that? How can you predict that any "marriage" between two lesbians would be a good thing?
But I can safely say without hesitation that such a s "marriage" would be unnatural, sterile, as well as sexually, psychologically, and socially dysfunctional.
I need not know anything about the traditional marriages in your cul de sac to reach such a conclusion.