The story of Derek reached me later, and I cannot honestly claim I saw any of it. Mia eventually described the night to me, and another friend confirmed the broad outline, though the details differed depending on who was doing the telling. Sarah had gone to meet Derek, a man she knew through work and whose messages had become more frequent over the preceding weeks. She expected that evening to mark the beginning of something serious; he apparently understood it as an informal date.
They had dinner, drank, and talked in a way that left Sarah excited and uncertain. She told Mia afterward that she had expected me to call repeatedly and demand that she come home, and she had been checking her phone between conversations. When no call came, she began checking more often. By the time she returned to the apartment after three, whatever attraction she felt toward Derek had been overwhelmed by her disbelief that I was gone.
I do not know precisely what happened between them that night. Sarah later said they did not sleep together, and I have no evidence one way or the other. The question mattered painfully for a while, and then it mattered less than the fact that she had used him to declare the end of our relationship. I did not need a more dramatic betrayal to make that decision count.
A week or so later, Sarah saw Derek at a bar with another woman. Several people from their social circle were there, and according to the accounts I heard, Sarah confronted him in front of them. She demanded to know why he was seeing someone else, and he told her they had only gone out once and had never agreed to be exclusive. The argument was public enough that the details spread through our acquaintances faster than either of them could control.
I learned about it on a Tuesday afternoon from a text I did not ask for. I stared at the message and waited for satisfaction to arrive. Instead I felt tired, as though someone had mailed me a souvenir from a place I had finally managed to leave. I deleted the conversation and went back to the proposal I was working on.
Not everyone was willing to leave the matter alone. One of Sarah's friends sent me a long message explaining that Sarah had been humiliated and needed a compassionate person in her corner. Another said I had made my point and should stop holding a grudge. A third asked whether I would consider meeting Sarah for closure, because apparently everyone would feel better if I did.
I wrote a reply several times and erased it. In the end I sent the same short answer to the people who contacted me: "Sarah and I are no longer together. I'm not discussing her with mutual friends, and I hope you'll respect that." The message did not make me look particularly generous or wounded. It merely closed a door I was no longer willing to stand in.