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.

I have never had any issues in 26 years although I can understand the concerns. As long as we are not talking about anal sex, judicious eating and judicious use of Pepto Bismol or Tums should nip gas concerns in the bud. My main Issue these days is ED, which sucks but has more to do with my age than my Pouch. Anyway good luck. 

I never had a j pouch but was functionally incontinent for years pre-k-pouch. Same protocol as Bill...light meal beforehand (or no meal), empty out as much as possible and RELAX. 

As for the conversations...you need to have a sense of humour.  So does he. You need to be able to discuss how you are feeling before, during and after...to feel free to say stop, wait, I need a break so that you can run and let the gas out or whatever...Then come back and feel comfortable. Also, put a pretty towel on the bed, something cute, not clinical like a white towel. Make sure that you keep a blue pad covering the mattress at all times (emergency measures) and prepare for the worst but expect the best.

A damp washcloth or a package of wipes near the bed help you to feel safe and fresh.

Sharon