I think some might say Star Wars is a part of “nerd culture.” Whatever that is. So it may not be because it’s Star Wars, but because sci-fi (sci-fantasy?) is one of those nerdy things. And culture says such things are more for guys.
I have no idea how to fix that. I wish I could. I’m filmly entrenched in it from multiple angles: Star Wars, Star Trek, Stargate, video games, board games… and the perception is that women are quite the minority of the fanbase for all of those. As well it seems many fans of any one of those don’t really intersect with the others.