I farted once during sex with the wife, missionary style. It was a loud trumpet fart too. We both just stopped, looked at each other for a few seconds, and then busted out laughing so hard that we couldn't breathe. We actually had to start all over when we calmed ourselves down.
I fail to see why it's such a big deal, everyone farts, it's a natural human act. When SK says that it could have been the reason for the demise of her marriage I hope to God she is kidding, otherwise that is shallow and petty as all hell.