Shortly after signing their prenuptial agreement the morning of Dec. 7 in Miami, Barbara Guggenheim and Alan Joel Patricof were, as usual, watching the clock. Not because they were counting the days until they were married — they are so in love, both said, that this was a given — but because that’s what their lifestyles dictate.

“I think breakneck is the only speed Alan knows,” said Ms. Guggenheim, who lives in Malibu, Calif. She wasn’t exactly idle that morning either. Before the ink on the prenup was dry, several clients were awaiting her at Art Basel, the international art fair that brought her to Miami.

Ms. Guggenheim, 77, and Mr. Patricof, 89, have known each other since the early 1970s, before either had established what would become formidable reputations — Ms. Guggenheim as an art adviser to clients including Tom Cruise and Steven Spielberg, and Mr. Patricof in business.

Both were living in Manhattan when a mutual friend, the art historian Jonathan Brown, brought them together for dinners on the town. They were a party of six in those days: Ms. Guggenheim and an art dealer boyfriend, Mr. Patricof and his wife, Susan, and Mr. Brown and his wife, Sandra (Mr. Brown died in 2022).

The meet-ups were infrequent, both recall, but the company was memorable. “Alan liked new adventures,” Ms. Guggenheim said. “He was always willing to try out new restaurants. And he was lively and interested in art history or whatever the conversation was.” Mr. Patricof liked Ms. Guggenheim’s passion for art, and her hustle. “Barbara was always very knowledgeable and hardworking,” he said.