Don't all groups do that somewhat? Even women. Or hockey players. Or Italians. I would say no.

There are many, many "sub-communities" in life, there's nothing separatist or unfair about that. Model train enthusiasts have their own language and culture, so do soccer fans and gays and Christians. What makes it separatist is when someone starts to believe that their group identity is more real than their humanity -- as a source of their basic answer to "who am I?". Once you start thinking "... if we could only get rid of those others", that's when you know you've crossed the line from a simple membership to zealotry.

Maybe, but what of it? There's nothing wrong with self-chosen separatism (at least in a pluralistic and generally egalitarian society such as the US and most of Europe). Although we have a negative connotation of "ghetto" from the past half-century or so, it was perfectly normal and natural for newly arrived immigrants to the US to settle into their nationalistic ghetto. That's where their families and friends lived, where the food that they liked could be found easily, where their churches and synagogues were ... it's where they chose to live. Now, when someone (outside the ghetto) puts up a wall around the ghetto and says "you may not cross that wall" then it becomes an enforced separatism that we frown upon. Likewise, if homosexuals want to maintain their own associations, bars, businesses and gatherings (and especially if they don't overtly ban others from joining, which I don't see to be the case), then there's nothing at all wrong with that. It's when one erects a sign on an establishment that says "No Gays Allowed" that a line is being crossed. (Not that I think that's right, either. I think that private associations have the right to exclude whoever they want on whatever stupid basis they want to establish. But the US Supreme Court doesn't agree with me.)