After we got our pool my wife’s friends would could over to swim. One night after several drinks my wife decided she was going to bed. That left two of her friends and me to continue to swim. After a bit, I started to realize one of the girls was causality flirting with me. I thought this was strange at first but also made me think this was a set up. She would swim close to me and brush my crotch. Obviously I started to get hard. The other girl was obvious to any of this. The next time she swam by me I reached out and felt her breast. Her nipple was growing in my hand. Then she swam away with a smile. After a bit the other girl got out and sat on a chair by the shallow end of the pool. My new friend and I floated close to her. Being that is was dark and the pool lights where off she did not know that I was stroking my wife’s friends clit and putting my finger deep inside her. The girls keep on chatting then I felt her pussy start to contract holding my finger in place. The other girl never new, and thankfully my wife now ex wife never found out.
Source: reddit.com/r/Erotica/comments/zn9213/fingering_wifes_friend