“I kept getting teased about dating a cougar,” Mr. Mann said, laughing. “But the age difference never really bothered me because we just hit it off, and I wasn’t about to let her go.”

He held on tighter with each passing season, and then in June, after one of their many late-night drives home from the Metropolitan Opera House in Manhattan, she decided to buck tradition.

“I asked him to marry me,” she said with a chuckle. “I was tired of chasing after him.”