Short summary of my situation: I stayed with my fiance’s little sister, Mary, during a work trip. While drunk we started an affair, that lasted for the time I spent there. We agreed not to tell anyone.
However she came here for an extended stay to visit her family. We never discussed what we would do, if we saw again. As no one else could make the two hour drive to the airport to pick Mary up, I went to pick her up alone. We ended up fucking in my car in a secluded piece of wood on the way back. Following that we talked a little about us and where this all was going, we agreed it was just very great sex, but without emotional attachment.
My fiancee wasn’t home and Mary came over to wash some clothes. I am between work projects so I don’t have to be in the office, outside of doing work on the daily mail addressed to me. So I was home when Mary came over. I helped her getting her laundry ready and into the machine. As her big sister was at work, Mary decided to take the opportunity and have some fun.