This has been my experience as well. It's sad, really. All of the (few) female gamers I've been in groups with - both as a player and as GM - have been excellent roleplayers and quite skilled at RL group dynamics, as well.

There was one girl back in college who was phenomenal. The very first time she played it was by accident. One of my regular players dropped in to see me and she was accompanying him. After the two of us males had been talking about the current campaign for a bit, she asked us, "How do you play this game, exactly?"

We two males looked at each other for a moment, then I said to her, "Okay. Take a moment and imagine yourself five years from now." After a moment, I added, "Okay, now describe your future self." She gave us a detailed account of living in Atlanta, working for an interior design firm, having an okay apartment and driving a vintage 65 Mustang. I thought a moment, then replied, "Okay. One fine spring morning you're driving in to work and you keep seeing the same large black SUV following you. Or at least it seems to be the same one and each time it disappears it's always reappears a moment later." Before I could even ask for a response, she blurted out, "Damn! I need a bigger car." And we were off!

Sadly, she and that guy she first appeared with soon became boyfriend/girlfriend and then fairly soon thereafter became not. And that was the end of that.   

There was another excellent female player who was part of a group I used to play with in Knoxville. A beautiful girl, a violin major at UT and French-Canadian (accent and all). Yep; She was the apocryphal "Canadian girlfriend," in the flesh. But then our GM of that time started hitting on her and she promptly vanished.

I suppose it's sort of like interoffice romances, except without an HR Department on call to (hopefully) keep things in line.