Could it be that she likes having sex with you but she doesnt enjoy masturbating?? Some woman, me included do not like to play with ourselves (finger ourselves). I dont know but to me thats what it sounds like. If she was having second thoughts as the previous poster suggested, I couldnt see her saying things that could get you aroused or saying that you are sexually compatible..... just my opinion anyways.
Re:she Is Too Shy About Verbalizing Sexual Needs And Desires
My advice - Learn about the culture. Never talk about sex before you become intimate. It's not the done thing. I found useful information about values and culture of Latvian and Russian women from a local dating site www.randevu.lv
Hope this helps.
Maybe she is a little bit more comfortable over the phone, internet.. ect.. but in person she gets embarassed and I agree that it could be related to her culture. But talk to her about it, it could be anything. Good luck.