Hold on now.
I've experienced "blue balls" and it is not fun. I felt serious pain. It's not weather or not you've had it for a long time, it's a condition that happens when you get very aroused and don't get it. Like your going to and then someone rings on the doorbell interrupting you. I've never used it as an excuse to get sex. That's just pathetic, if you can't get it don't use blue balls as an excuse. One true thing though is that masturbation helps. You gotta choke that chicken.
But if she says she's going to give you blue balls then it sounds like that's all your getting.