Hi, first of all I would like to thank everyone so much for their replies. It's all been really helpful, particularly in the sense of confirming that things are not right.
In answer to some questions, no, I don't provide a mealticket, the bills are split equally. Yes, this has been happening more frequently, although it happened at the beginning of the relationship too. I think there is a real problem with quickness to anger, and it needs looking at. It's something we all have as children and teens (she's 41), but something we need to check on as an adult and ask is this justified in this situation.
We have had loads of converstions about this til I am blue in the face and even did some counselling sessions for a while. My conclusion now is that she is not comfortable with intimacy and finds it hard to open up. (I am sure by now you are all starting to ask 'What kind of relationship is this?'.)
The response that Jeff wrote really resonates with me because I do feel it will affect who I am and my capacity to give if things do not change or if I don't consider something as radical as leaving.
Anyway, once again, thanks for everyone's input.