I can't give you any stats but can give you my personal experience and hopefully put your mind at rest. I'm female and have had genital herpes for nearly 30 years now. When I was first diagnosed, I thought it was the end of the world, but really, it isn't - worse things can happen.
The first thing I want to tell you is that I've been married for nearly 20 years and my husband has not got it from me. We've just been sensible and done what we thought was best, which was no sex during an outbreak and really waiting until it had cleared up. I always keep my towel separate from the rest of my family during an outbreak too.
Until a few years ago, I suffered monthly outbreaks of herpes, sometimes more than once a month and it really got me down. I now live in Germany and my GP (who practices homeopathy too) suggested I have a course of 10 injections to boost my immune system (here it's called Eigenblut Therapy). It's an alternative therapy, used more often in Europe than in the States and I think the English name for it is Autohemotherapy. What happens is that a small amount of blood is taken from a vein in my arm and mixed with something (not quite sure what it is) and it's then reinjected into the muscle of my buttock. After each treatment, I've stayed clear for just over a year and then when it starts again, I just get another lot of injections!
This treatment has been like an absolute miracle for me. I get about one to two outbreaks a year now (if that) - it's not a cure, but has improved the quality of my life (and naturally my husband and family) so much!!
Please don't give up on your girlfriend, it might seem awful at the moment but I promise you things WILL get better and you'll learn to live with it, so much so that you won't really think about it any more.
I hope I've been of some help to you and please pass this info onto your girlfriend. Take care.