During the 30 years I had a J pouch, I would be sure to empty before having sex. It was also helpful to eat lightly beforehand. In my case, it seemed that knowing what I would be doing had an effect in slowing bowel activity and preventing accidents. Anyway, you should explain fully about your condition and the possibility that you might have leakage during the act so there will be no surprises if it happens. Try to forget that you have a J pouch and enjoy your encounters to the fullest.