I completely ruined my rationality, which I was devoted to, and I cheated on my father's G-spot press

Since my mother passed away early, my father and childhood friend Suremi, who had raised me alone, were the ones who supported me as I was depressed. They were childhood friends who had always been close to Sumire, but they had been dating for about a year and they had been thinking about getting married to each other. Then, to inform my father that he was getting married, the three of them set up a meeting with Sumire, but I didn't notice that what his father was doing at the time was wrong...