Intimate photo shoot and prohibited sex with elderly mother-in-law

My girlfriend and I had a little surprise for our close friends. We wanted to take some intimate photos of her, and we asked our friend's mom to help us out. She agreed, and we started the photo shoot. Everything was going well until my girlfriend and her mother-in-law got a little too close, and they started to flirt with each other. I knew that my wife was always up for anything, but I didn't expect my friend's mom to be so interested in her. It was a bit strange, but my girlfriend didn't seem to mind. After a few more pictures, my girlfriend and the older woman started to get a little more intimate. They moved to the couch, where my girlfriend started to straddle the older woman's thighs. The sight of the older woman's hairy beaver made my girlfriend's eyes light up with excitement. The two of them continued to explore each other's bodies, all while my husband was in the room, completely unaware of what was happening.