My wife and I have an open relationship. We have had other partners and group sex quite a few times. Even though we don't consider that as our lifestyle since we don't go out of our way to do it all the time, we do consider sex to be fun and natural when the opportunity presents itself. In fact, we currently share a house with a friend a few years younger than us. He and my wife have sex as regularly as we do, which means my wife is pretty much getting it constantly! I am not involved in any extramarital fun at the moment. But a few years ago, I overheard my wife on the phone with her older sister discussing her impending fortieth birthday. I could tell from the conversation that her sister was asking if she might hook her up with one of her young boy toys. I raised my hand in indignation and said, "Hello! Right here!" My sister-in-law does not live close. So, the next time she had to make a business trip to our area, she let me know at what hotel she would be staying. My wife even sent me off dressed and smelling nice. She only told me I needed to be back in time for her to take the car to work the next morning. When I knocked on her room door, she answered with a big, bashful smile. We hugged and kissed like we do when we see each other on holidays. We sat down and watched TV while we had beer and pizza. We had a laugh over how we had both always found each other attractive but figured there was no way the other felt the same. We were both nervous, so I sat close to her so I could massage her bare feet. That really opened her up. We began to kiss. She told me how much she liked to kiss and that she never got that kind of affection anymore. I lifted off her shirt and began to touch her. She kept saying that she couldn't believe I was there because I wanted to be, and that her forty-year-old body must be gross to me. I said she was silly and that she shouldn't be ashamed just because she didn't have a body that people use in beer commercials. I enjoyed telling her all the things about her that turned me on like how beautiful she was, how perfectly shaped her legs were, and how smooth her skin was. I took off my clothes quickly. Then I pulled her jeans and panties down much more slowly. We had sex for about forty-five minutes. We took a break after that and she told me how comfortable I made her feel and how much fun she was having. We made out on the couch again and then we went back to the bedroom to spend the night. She warned me that she wasn't a snuggly bed partner. She thought we were done having sex, but I told her I wasn't finished with her yet. We had oral and regular sex several times after that. When she finally relaxed, we hugged and kissed. She babbled a bit about how she never knew it could be that way, and was that how sex was for her sister all the time? I humbly admitted that it was, and that I wanted to do the same for her any time she wanted. She said she guessed she was wrong about not being a cuddly sleeper as she laid her head on my chest and we fell asleep. In the morning, we woke up late. Even though I could just barely make it home on time, we knew we had to do it again one last time while we had the chance. She seemed amazed that the morning sex was almost as good as last night's. Even though my wife and her sister are a little bit weirded out about it, just because they're sisters, I can't wait to get the chance to do that again!