The moon was full, and its silver light cast shadows into every room in the house. We had been partying and I laid on the couch listening to the quiet. Then I heard what I had been waiting for, those muffled moans and creaks of the bed that cannot be mistaken. I got up, adjusted my already half hard cock, and walked toward the master bedroom. The house was dark, I was silent and to my surprise the door was half open and with casual confidence I stepped into the frame. My best friend was straddling her husband and grinding her hips forwards and back in rhythm to silent music. Her mouth watering tits swayed and bounced hypnotically, the nipples stood out firm with arousal. As if possessed I simply opened my pants and pulled out my cock to enjoy their intimacy as if I was invited. The moonlight threw shadows but also made her fair skin glow with sharp detail. Lost in the mesmerizing movements of her body my eyes darted from her heavy tits, around her curves and to her soft ginger pubic mound, but when I looked back to her face she was looking right at me. My heart raced, I had been caught, but then she did something that almost made me loose it right then and there. She smiled at me and bit her lip. I have never been so hard and seeing her smile I continued to stroke myself while my best friend gave me a show. We held eye contact until she threw her head back, let out a deep groan of satisfaction and fell forward. Entirely satisfied, I woke on the couch and we all had breakfast without saying a word about anything after the party. She and I would share this secret intimacy several more times and I would always remember it passionately.