This is one issue where I'm relatively "live and let live". Why should I care if two people of the same sex want to have a relationship?
Same-sex relationship have existed since ancient days (as have non-marital heterosexual relationships), ... yet they have always been differentiated from the marital state.
The facts stated in this thread's text have been gleaned from over 50 years of study regarding the nature of homosexual relationships.
Save for a select few ... none of these relationships resemble monogamus marriage in the least. As even long-term male homosexual relationship regularly involve orders of magnitude more promiscuity than comparable heterosexual relationships ... they would present a distorted picture of marriage if they were to be identified as such.