Over sushi (which I was too embarrassed to admit I’d never had before), I learned all about his age, his daughter, his drink-and-drug-filled past. The only other alcoholic I knew was my father, a violent, watery-eyed creature who had never been sober for 12 consecutive days, let alone 12 years. This handsome man sipping green tea seemed to belong to an entirely different species. And unlike my fragile, bipolar first boyfriend, he radiated physical and mental health.

After dinner, sitting behind the wheel of his ancient Volvo in the sushi bar parking lot, Theo took a deep breath and turned to me. “I — — ” he began.

Assuming he was going to say something benign like, “I had a nice time,” I cut to the chase and kissed him. When he kissed me back, I felt weak knees and a flash of recognition: yes, this is it.

We spent the next few evenings talking in restaurants, then making out in Theo’s car. I liked the way it was progressing, with a kind of passionate restraint. He seemed to be holding back because of my age, so all we did was talk and kiss. One night when I made a move to do more, he stopped me and finished the sentence that I had interrupted at the end of our first date.

“I need to tell you something,” he said. “I’m H.I.V.-positive.”

While I sat beside him in stunned silence, he described testing positive four years earlier, in 1988, and how the doctors had given him no chance of long-term survival. But he was sure he’d been infected all the way back in 1980 by a needle shared with a friend who had since died of AIDS. If so, Theo had carried the virus for 12 years and, according to recent blood work, his immune system still showed no signs of damage. Nobody knew if it was due to his sobriety, his healthy diet, a genetic quirk or just dumb luck.