When my wife went home to visit her parents, it turned out that my sister-in-law and her husband were also visiting. My sister-in-law was even more beautiful than my wife, and I found myself staring at her repeatedly, drawn in by her allure. I started fantasizing about what it would be like to do various things with her. Then, unexpectedly, my sister-in-law made a move on me! Even if it's only an in-law relationship, since she's technically my sister, this is incest… My sister-in-law got excited from taking me away from her sister, and I got excited from being taken away by my sister-in-law.
