When my husband, Greg, suggested that we spend one week with another couple to “make our marriage more exciting,” I thought he was joking. He wasn’t. He wanted me to stay with his friend Marcus while he spent the week with Marcus’s wife, Lydia. I watched him explain the idea with a confidence that made my stomach turn. He seemed convinced I would cry, beg him to reconsider, or accuse him of being unfaithful.

Instead, I smiled and said, “All right.” Greg looked surprised, but he quickly hid it behind a grin. What he didn’t understand was that I had already noticed the late-night messages, the unexplained trips, and the way Lydia suddenly appeared wherever he went. I agreed because I wanted to see how far he was willing to take his own idea. And when the week finally began, I made one phone call that would change everything.