Are gay men more transient?
Many variables involved, like job market, age, education, community gay acceptance, etc. I also think it's logical to assume, though harder to prove empirically, that without the obligations of legal marriage, without wife & children, a gay man has less firm ties to a place.
I've observed the demographic impact of what the OP is encountering. When I was younger I was more in contact with the 20, 30 & 40-something crowds, and there was a fairly high turnover due to relocation, at least among the single guys. Schooling & career are still very much in flux, and that brings geographic change.
But as I got into my 50s and now 60s, with most of my friends close to my own age, there is little movement and change. The set of friends I established when I myself relocated here 6 years ago is virtually the same today.
But then they are almost all couples, both gay & lesbian, own homes and are approaching the end of their careers. Big changes at this point are unlikely, although a few lost jobs from the Bush Recession several years ago.
But even they remained in the area, wanting to keep their homes and lives they had created here. In several cases other gay friends helped them to begin new careers, and all are doing well now. I've always been impressed with the safety net the gay community can provide, maybe because we've all been through different forms of adversity ourselves.