“I was really struck how easy it was to talk to Jenny,” he said, “how genuine she was, how caring.”

They walked around Central Park that afternoon,and later went for sushi and to a bar on the Lower East Side. By the end of the date they agreed to try a long-distance relationship, and parted with a kiss.

Over the next two and a half years they braved flat tires on the New Jersey Turnpike, surprise winter storms and train delays. They celebrated Chinese New Year with her family, and Passover Seders with his.

During the summer of 2017 Ms. Lu visited him in New York and Hong Kong, while Mr. Rotblat, now 30, interned at the law firm Debevoise & Plimpton. He is currently an associate in its tax practice in Manhattan.

“I was applying broadly to med schools mostly along the East Coast,” that summer said Ms. Lu, 27, now a third-year medical student at Albert Einstein College of Medicine in the Bronx. “He’s always been my greatest support system.”

In the summer of 2018, they got an apartment in Astoria, Queens, and six months later he planned to propose in Philadelphia while they visited his parents the week his brother, Jeremy Rotblat, a Fulbright fellow in Tajikistan, was in town.

“In the middle of the night I woke up feeling awful and Jenny said I should do a video call with a telehealth doctor who prescribed antibiotics,” said Mr. Rotblat, who came down with a head cold, fever and bad case of conjunctivitis. Before they headed to the local pharmacy, Mr. Rotblat got down on one knee at 3 a.m. “My future doctor was right there.”