Let me preface this with saying that my relationship with straight women are quite dynamic. To be honest I have very few straight girlfriends, and have never had a relationship with one that was very close (not including family). That's why I never understood why some women were called a "fag hag"? Most women I know are strong, independent, direct, and will not take any crap from anyone. So, what is a fag hag (god I hate even using the word), and why do we refer to women like that? Or maybe the term is antiquated and out-of-date? I had to ask several people I knew so that I could understand why it's used and is it still used. To my surprised three of my friends say that the term is still used and they have no problem using the term "fag hag".
So, as I understand it a "fag hag" is a women that tries to avoid romantic entanglements with men, and dedicate their energy into relationships they have with gay men. It's like the affections they receive fills some void and maybe feels like "the real thing." They can even harbor deep feelings about their gay friends - a fact that is sometimes alluded by both parties, just never discussed.
This is what was told to me by one of my friends, picture it this way - "a narcissistic gay man who is just being a dick to his number one "fag hag" who has no backbone. Thy gay guy uses her to feel beautiful and inflate his over the top ego; while she has little self-worth and feels somewhat special just being in the presence of a gay man".
I've never had this type of relationship and quite honestly it doesn't interest me; it's seems like a bullshit premise of a friendship. There is an argument that that the gay man/straight women relationship has some moments of co-dependency, like Will & Grace. There is no doubt that any friendship can get to a level of intensity that at times become uncomfortable, but that might just be a by-product of a close friendship, and isn't exclusive to gay men and straight women.
Most of my aversion to this type of friendship is based on annoyance and frustration. I mean at some point in our lives we have had a girl tell you "Oh my god, you're gay. I need a gay friend, and you're so funny. Can we hang out?" It's almost as if they are being progressive by befriending a gay man, but to be honest it could be offensive.
What I find more offensive is that some gay men really feed into it. They're more than willing to go along and be the "the gay best friend", which I've never completely understood. Homosexuality in our current culture have complicated the sexual identity of gay men. It's like there are certain expectation for us on how we're supposed to act and dress. We try to fight this stereotype, but we sometimes fall into the typical roles that we're expected to play. I can be honest, there have been times that I'm guilty of being somewhat bitchy out of some misguided sense of obligation.
I can say that I'm proud that any straight women I know are not "fag hags". They are very strong women, with stable relationships, and trust me none of them want to have sex with me or make silly remarks like "I wish you were straight!" While my sexuality is a defining part of my identity it isn't the reason why I have certain friendships.