John Bayley, left, with his wife, author Iris Murdoch, having breakfast in 1986. Mr. Bayley later wrote an acclaimed memoir about Murdoch’s struggle with Alzheimer’s disease. (Terry Smith/The LIFE Images Collection/Getty)

John Bayley, a British literary scholar who was married for more than 40 years to the novelist Iris Murdoch, and whose intimate memoirs of her descent into Alzheimer’s disease were alternately praised and criticized for their unsparing revelations, died Jan. 12 at age 89.

Robert Weil, his longtime American editor, confirmed the death at Mr. Bayley’s vacation home in the Canary Islands. The cause of death was described on the death certificate as “heart insufficiency.”

Mr. Bayley spent most of his career as a professor and literary critic at the University of Oxford. He was a popular teacher and wide-ranging scholar, and his expertise extended from Shakespeare to Jane Austen to Russian writers Pushkin and Tolstoy.

In 1956, he married Murdoch, a formidably intelligent writer who published more than 25 novels and won Britain’s prestigious Booker Prize in 1978 for her novel “The Sea, the Sea.” Writer John Updike once called her “the preeminent English novelist of the second half of the 20th century.”

In the 1990s, Murdoch developed Alzheimer’s disease, and Mr. Bayley cared for her at their ramshackle, overstuffed house in Oxford. Weil, then an editor at St. Martin’s Press, suggested to Mr. Bayley that he write about the experience.

“Elegy for Iris” — titled “Iris: A Memoir” in Britain — appeared in 1998, when Murdoch was in the final stages of her disease. She died in February 1999 at age 79.

The book became an international best-seller and was among the first and most eloquent memoirs to address the tangled emotions of living with someone with Alzheimer’s disease.

In “Elegy for Iris,” Mr. Bayley, who was six years younger than Murdoch, described their first meeting, when he saw her riding a bicycle in Oxford. He wrote of his own sexual inexperience and about Murdoch’s lusty approach to life, including her affairs with both men and women, even after they were married.

Murdoch, who explored rigorously intellectual ideas in her novels and who wrote one of the first books in English about French philosopher Jean-Paul Sartre, later reached the point where she was no longer aware that she had been a writer.

Mr. Bayley attended to her at home, feeding and dressing her and turning on the television so she could watch the children’s show “Teletubbies.”

Novelist Mary Gordon wrote in the New York Times Book Review that “Elegy for Iris” possessed “a greatness that must be seen simultaneously in literary and moral terms.”

“In its evocation of the lyrical, the comic and the tragic,” Gordon concluded, “this splendid book enlarges our imagination of the range and possibilities of love.”

Other readers were less receptive, saying Mr. Bayley’s descriptions of his ailing wife were unseemly and cruel. Novelist Muriel Spark called the book “sordid.”

Historian Gertrude Himmelfarb, writing in Commentary magazine, denounced it as a form of “spousal abuse” and “a violation of [Murdoch] as a mature, dignified person, an eminent thinker and writer, and also a violation of her expressed will and intention to preserve her privacy.”

Mr. Bayley remained unperturbed, believing his memoir honored the life he and Murdoch shared.

“I didn’t mind being criticized and I quite saw their point,” he told Britain’s Daily Mail newspaper in 1999. “But I was totally confident that Iris wouldn’t mind and would be happy for me that the book became a success.”

“Elegy for Iris” and a second memoir, “Iris and Her Friends” (1999), became the basis for a 2001 film, “Iris,” directed by Richard Eyre. Murdoch was portrayed by Kate Winslet and, in her later years, by Judi Dench; Mr. Bayley was played by Jim Broadbent. All three actors were nominated for Academy Awards.

Washington Post critic Ann Hornaday called the film “one of the great love stories, an epic romance” and a “precise, graceful and intellectually rewarding work worthy of Murdoch herself.”

John Oliver Bayley was born March 27, 1925, in Lahore in what was then British-controlled India. His father was an army officer.

He studied at Eton, one of England’s renowned prep schools, and served in the British army during World War II. He graduated from Oxford’s New College in 1950, then stayed on to teach literature at the university until 1992.

Mr. Bayley published many well-received scholarly books, including studies of English poetry, Russian literature and Shakespeare, as well as wide-ranging essay collections. He was considered one of the foremost critics in the English language and often wrote for the New York Review of Books and other leading publications.

After publishing a novel in 1955, he concentrated on his academic work for almost 40 years before returning to fiction with several new titles in the 1990s.

A little more than a year after his wife’s death, Mr. Bayley married Audi Villers, a widow and longtime friend who had helped care for Murdoch during her illness. Villers is his only survivor.

Murdoch was aware of her failing powers during the early stages of Alzheimer’s disease, saying, “I am sailing into the dark.”

Mr. Bayley evoked that comment in the final lines of “Elegy for Iris.”

“She is not sailing into the dark,” he wrote. “The voyage is over, and under the dark escort of Alzheimer’s she has arrived somewhere. So have I.”