They continued dating, traveling back and forth from New York to St. Louis and taking trips together. “She was easy to fly with, the easiest woman to travel with I’ve ever known,” he said. “She just has this laid-back attitude.”

Ms. Shull recalls first seeing Mr. Long’s apartment full of bikes. “I loved it!” she said. “On top of being cute and super smart, he’s a crazy good athlete in crazy good shape.”

In spring 2003, he persuaded her to move back to New York, which she did without hesitation. “She doesn’t have any problem picking up and leaving,” he said.

Over the next several years, the two lived in a high-rise building in Hell’s Kitchen; a house in Greenwich Conn.; an apartment on Manhattan’s Roosevelt Island; and another in Long Island City, Queens. In 2003, she founded ReThink, and in 2004 they acquired two Yorkshire Terriers. She taught him to ski and he encouraged her to go on long bikes rides with him, promising brunch somewhere along the way.

They even briefly discussed trying to have children together (neither have children from their first marriages) but decided against it. She regrets that. “What I know is that even in situations where there’s nothing that can be done about it, you admit to the whole spectrum of feelings and the regret becomes less debilitating,” she said.