We found that set in stone rules don't work for us, we go with guidelines. That cane from experience with rules either causing missed opportunities that really should not have been missed or just realizing stuff happens some times.
Ie some couples have a no kissing rule and if it gets broken it causes issues. Better to have a no kidding guideline with the understanding that in the heat of the moment it might happen and you just calmly talk it out after and move on.
I was both a little annoyed and turned on if course . she plays alone a lot and sometimes I only find out after the event.
It's about trust, I trust her, so no need to always announce things in advance. Also sometimes things just happen.
After assuring the friend I wasn't going to attack either of them, I asked him to get dressed and leave. Then took her myself.