Well, as a guy, I get sorta grumpy or pissed off if I don't achieve an orgasm while having sex. Maybe thats a bad thing but, I think alot of guys have the same deal going on. So your girlfriend has basicly a guys point of view on this. I used to go out with a girl that took some sort of weird medicine, it made it almost impossible for her to reach her climax, and it frustrated me because regular sex never even put her close. I know it might be selfish but I hate orally pleasing a woman. It's nice to feel but not to look at.
Bryan