Jide Zeitlin, the chief executive of Tapestry and one of only four Black chief executives in the Fortune 500, resigned on Tuesday and later said the unexpected move, less than a year into his tenure, was related to a past relationship. The company’s board had been made aware of a misconduct allegation involving Mr. Zeitlin and hired a law firm to investigate, according to a person familiar with the situation who spoke on the condition of anonymity.

After Tapestry, which owns the Coach and Kate Spade fashion brands, announced that Mr. Zeitlin was stepping down for “personal reasons,” he released a statement saying the exit was tied to a past relationship with a woman. In a letter posted to LinkedIn on Tuesday afternoon, Mr. Zeitlin elaborated, saying the relationship started and ended 13 years ago and had nothing to do with his role at Tapestry.

“I did not use power, wealth or position to further that relationship,” he said. He said it was a mistake in his personal life that he had dealt with at the time.

In the LinkedIn post, Mr. Zeitlin said the relationship was “with a woman I had met while pursuing my interest in photography.” Mr. Zeitlin, who spent two decades at Goldman Sachs, said he sometimes used a pseudonym based on his middle name, James, when photographing strangers in order to protect his privacy as he rose “through the ranks as a rare Black banker.”

The executive claimed that the relationship had recently become an issue because William D. Cohan, a journalist who has written for publications including Vanity Fair and The New York Times, was asking questions about it while working on an article about Mr. Zeitlin. Mr. Cohan acknowledged in a statement that he had been working on a story about Mr. Zeitlin and Tapestry with ProPublica.

“I reached the conclusion this past weekend that this distraction will not allow me to meet my responsibilities as C.E.O.,” Mr. Zeitlin wrote.

Tapestry hired the law firm Fried, Frank, Harris, Shriver & Jacobson to investigate Mr. Zeitlin’s conduct, the person familiar with the matter said.

Tapestry, which is based in New York, said that Joanne Crevoiserat, its chief financial officer, would serve as interim chief executive and that it had started a search for a permanent replacement. In March, Tapestry had said Mr. Zeitlin would remain at the helm for at least three more years.

Mr. Zeitlin’s departure comes as the retail industry grapples with the fallout from the coronavirus pandemic. Tapestry, like other retailers, has been forced to close stores and adjust operations in China and the United States as the virus continues to spread.

The company, which also owns Stuart Weitzman, is a giant with about $6 billion in annual sales, but its shares have dropped by roughly 50 percent this year. It next reports earnings on Aug. 13.

Mr. Zeitlin, who is married, became the Tapestry chief in September; he had been the company’s chairman since 2014 and was a board member before that. As part of his exit, he also resigned from the board.

Mr. Zeitlin was previously a private investor overseeing the Keffi Group, an investment office.

Born in Nigeria and adopted by an American family as a child, he attracted praise and attention last month for a staff letter, later published on LinkedIn, about civil rights and the Black Lives Matter movement. He went on to discuss the protests and the importance of antiracism and diversity in corporate America on shows like “Good Morning America” and “Face the Nation.”

In its announcement on Tuesday, Tapestry praised Mr. Zeitlin for his leadership, including his work during “these unprecedented times” and his “key role in driving the development of Tapestry’s strategic growth agenda.”