Details

My parents remarried and my two step-sisters were actually having an affair! I thought they got along really well, but they were sisters of the same sex, so I thought that was all there was to it, but it turns out they were more than just sisters! They would flirt with each other when my parents and I weren't looking, and when I wasn't around, they would have intense lesbian sex! It was an intense lesbian sex scene with a sense of immorality that should not be discovered by the family, but I happened to see it. Then she told me to keep it a secret from our dads, and it developed into a threesome! In the end, I also ended up getting caught up in a forbidden relationship, hiding it from my parents!