I decided not to tell my date I had taken the hormone. [Neuropsychologist Marcel] Kinsbourne had explained that if just one person acts more comfortable and interested, it can spark a natural release of oxytocin in the other person. …

We took a tiny table in the middle of the room. It was a brightly lit, busy place, and the waitresses were screaming loud orders in Shanghainese. It wasn’t romantic, but I didn’t care—I was in a very good mood. And my date definitely seemed more confident and relaxed. I sensed that he liked this calmer version of me better than the very intense and chatty version he had met before. We took a long walk home, and, for the first and only time, I imagined us as a couple. …

After our very affectionate date, I was excited to meet him again a few days later. I didn’t take oxytocin this time. He came to my place for pancakes, and I was a little nervous. As he sat there in my kitchen, we suddenly had nothing to talk about. It was back to stiff conversation. I didn’t find him very attractive and got annoyed that I had to come up with things to talk about. I think he could feel it, and after we said goodbye, he sent me a text thanking me for the pancakes. I never heard from him again.