Re: the original topic, I would imagine the percentage of same sex marriages is really low because the ability to connect for young gay people has greatly diminished. As much as they are "out and proud", their lives are online now. My partner and I met 30 years ago at a bar, which was then the way to meet someone in person. That opportunity rarely exists these days because everything is online. There are far fewer opportunities to meet these days for younger people, so most of the gay marriages are most likely from older people who were together for years prior to gay marriage becoming legal.
Re: gay divorce, anecdotally we live in a small enclave of homes in a suburb of Dallas. It is by no means considered a "gay" neighborhood and tends to be 50 y/o and up. In our straight/gay circle of friends there are 4 gay couples (including us) and 1 lesbian couple. All are married and have been together for many years. 3 gay couples have left... one to move to a 55+ community, one to move to Colorado and the other because they adopted children. I have no idea how many gay divorces there are but we have gay friends throughout the country and their marriages are all going strong.