Shortly after Olivia Landau discovered Kyle Simon in July 2013 at the Gemological Institute of America in New York, where each was studying precious stones, she went underground to unearth more information about him.

“Kyle was so handsome, and I noticed that he often looked at me at school, and I definitely wanted to have a conversation with him,” said Ms. Landau, who was then 23. “But I realized that he was too shy to approach me and that became really frustrating.”

So one day after school, she decided to follow him into a nearby subway station.

“I always saw him taking the F train uptown, across the platform from me, so I just kind of stalked him,” she said. “I had no idea where the train was going, but I walked up to him and pretended to be surprised and said, ‘Oh, hello, I think I’ve seen you around at school.’”