[Always *]

Well, speaking as someone who WAS forced to have sex with an ex, I know how hard that situation can be. And for me, I think it was because I wasn't attracted to him anymore, and instead of having the respect for me that you have for your girlfriend, he would force me to have sex with him... Which is NOT the kind of relationship anyone wants to be in, I would actually consider it abusive...
So, I mean, it's good you've actually tried to talk to her, and aren't being a jerk about it and it is really unfortunate that she is flipping out on you like that. Though, just because for me, it was a loss of attraction, doesn't mean it is like that for her. She could just be stressed out over, I don't know, work, school, a fight with a friend, something that would put her off of being "in the mood". But fact of the matter is, either she'll come around and be more interested or she won't. It's only a matter of time