This summer we had pool parties at least twice a week. My wife friends would come over and enjoy bbq and alchohol. She has a male friend. I know they are close been friends for awhile. We would all hang out in the pool but I would notice he was always close to her. To be honest it would turn me on thinking what exactly he wanted from her. One evening everyone started to leave. I'm not a heavy drinker so I was sober so I volunteered to drive a couple home. I was going to get a ride back. My wife and hee friend were the last ones left . When I left they were out of the pool drying off. Told them I'll be back in a bit. So I was gone for about 20 minutes. When I come home I go through the front door not our side gate. I also get dropped off on the corner because where we live there is not alot parking. So they don't know im home. I walk to our kitchen window so I can see out to the pool. I see them in the pool. He is behind her kissing her neck and shoulders. His hand is all over her tits squeezing them. His other hand I imagined is playing with her pussy because she is squirming. I'm rock hard I start jerking off. Then I see her put her both hands on the side of the pool holding on. He must of pulled Her bottoms to the side and started to fuck her. Her face says it all. Head tilted back. Back arched he is pumping her hard. She turns i see her wrap her legs around him now they are kissing and fucking. He must of told he was cumming cause she got off and looked like stroked him and kissed him. They kissed for a bit more. They must of figured i should be getting home soon they got out and started to dry off. I went out and then came through the side gate. He said I can leave now just waiting for you to get home making sure everything was OK. We shaked hands and he left. I kissed my wife went inside. Told I was horny I fingered her she was so loose 3 fingers easily went in her and my cock was just sliding in and out.