Hi there
Well I get you.
If I had a girlfriend, I would expect her to make a move, when she is the one who wants it. Like at least teasing me, flirting, kissing and the what not.
Ummm
I think it is quite tricky. Maybe she is a bit shy about the before sex thing. But I think that maybe for her, as you are the man, even if she is the one who wants it badly, you are the one who must make all the work from the beginning till the end. Maybe for her all she has to do is just ask if you two could do it, and that is all. Like she just hints at it, and you as the man do the rest.
It is quite sad; not all women think like that but many do.
Have you considered talk to her about it?