My affair with my wife's friend "Rika" begins. A year ago, we were introduced through our spouses as couples, and since then our families have become close, sharing details about our personal lives. Drawn to Rika, who deeply values her family, I started meeting her secretly whenever I could between work. As our time together grew longer, she confided in me, saying she's desperate to have a child but is struggling with a sexless marriage. When I opened up about similar frustrations, she said, "I just want to forget everything, even if it's only for a single day." Jokingly, I suggested, "Why don't we take a two-day, one-night trip together?" After a brief pause, Rika nodded softly. "…Okay." Without telling our spouses, we head off on a two-day hot spring getaway. There, our relationship deepens beyond control.