Last weekend, something wonderful happened: friends came to visit.

But not just any friends. These were a special kind of friends—people we met when our adult lives were just beginning. We were newly married, still figuring out who we were, and dreaming about what life would be like.

Roger and I met Jeff and Paula Chipman in New York City when Roger was getting his Ph.D. at Columbia, and Jeff was starting medical school there. We spent countless hours together in our tiny one-bedroom apar...