My (now) wife had a torrid little 'affair' with a coworker of hers when we first began dating. She was in her mid-30's, he was around 18-19 years old. It began with him asking her to teach him what to do in bed, she asked for my thoughts, and I told her to go for it!
Since we saw each other only on the weekends, he would come to see her on their days off from work, and she was sure to let me know when he was visiting most times. It lasted for just a few months; once she moved in with me, it was too far for them to see each other regularly.
Unfortunately, I never got to watch, but she did eventually begin sharing details. And it still excites me to this day, some 30 years later, thinking of her taking his young, hard cock, and him enjoying the charms that only a more mature lady can offer!