Maye you can encourage her to let go..cause she might not know
and thinks she wants to urinate. Cause when she reaches her "peak",
it has the same feeling like want to urinate but, it is not. Its
just that she has reached her big "O" and hence, if she let go, er
body fluids will just gush out, wetting the bed even. I guess this
is the best feeling a woman can get when she have sex.
Try talking to her and encourage her...i am sure after that, she
will enjoy sex more.