Well, certainly you need to understand what happens during the sexual arousal cycle for women. There is a certain amount of swelling that takes place, and the urethra is a tiny little collapsible tube, so with sexual arousal there is a fair amount of swelling right around the urethra. As you know, the opening to the urethra is between the clitoris and vagina, and it is often difficult for women to urinate during sexual arousal. You probably also know that it is difficult for men, if even possible, to urinate when they have an erection for the same reason. The other possibility is that you may be somewhat dehydrated and therefore you do not have enough urine in the bladder with which to urinate. However, I would suspect the previous explanation of swelling due to sexual arousal as the reason for this. If you have any further questions, please feel free to get a hold of your health care provider and ask, but I am not surprised that this is an issue for you because it is difficult for many women to urinate when the tissue is swollen.