i dont really think you are a sexist pig as you put it, just a person with an intellectual view of what a woman is....
and to set your mind at ease, most women has a rule to follow (whether she knows it or not), but when she breaks this rule, it means that she is following her heart, cause the heart cant see any logic on anything......
scientist might say that what we, human, fell is based on one part of our brain's functions, and it would be easy to accept that if not to the fact that when we get emotionally hurt, it is truly felt by our heart (which again is explained as the overtime pumping of the blood based on the brains acceptance of data)...