After wearying months debating the possible breakup of their country, Canadians wondered last week if they were witnessing the crumbling of their leader's marriage as well.

Margaret Trudeau, wife of Prime Minister Pierre Trudeau, skipped her sixth wedding anniversary at home for an eight-day jaunt with the Rolling Stones rock group and other celebrities in Toronto and New York, and rumours of romantic ties with one of the Stones. She returned only at the last minute on Saturday to help her husband host a private dinner ofr visiting British Prime Minsiter James Callaghan and his wife.

Royal Canadian Mounted Police closed the road to Harrington Lake, the Trudeau country retreat 35 miles outside Ottawa where the dinner was held, and government spokesmen had nothing to say about details of Mrs. Trudeau's homecoming.

The Trudeaus were reportedly spending the rest of the weekened at Harrington Lake. Prime Minister Trudeau confirmed last week at a press a conference that his wife would be leaving today for Vancouver and a visit with her mother.

Mrs. Trudeau, who at 28 is 29 years younger than her husband, showed up at two Stones concerts in Toronto last weekened in the company of lead singer Mick Jagger, stayed at the same hotel as the rock group, then followed them to New York where she dropped out of public sight for a day or two. She resurfaced at a ballet in New York where she was accompanied by Princess Yasmin Ali Khan, the daughter of Rita Hayworth and the late Prince Ali Khan of India.

Later in the week, she visited the studio of New York fashion photographer Richard Avedon, where she had an appointment for photography lessons. Finally, she returned home to Ottawa aboard an Air Canada flight accompanied by an unidentified woman, after first annoucing in a New York intervies that she would not attend the Callaghan dinner because she had "abdicated" he role as Canada's first lady.

She later said she meant only that "I was going to abdicate from attending a public engagement in Nova Scotia later this month."

But she reportedly said she was tired of "shaking hands and smiling in crowded halls."

"I hope people will understand," she told the Toronto Star. "I really have had enough. I can only ask people to be tolerant of the fact that the . . . pressures of wives of politicians is very, very strong."

She also declared herself "insulted" by questions of any romantic link to the Rolling Stones. "There is no romantic involvement between me and any of the Stones. It's purely on the level of my being a fan and photographer," she said.

She added, "It has nothing to do with my personal relationship with my husband, which is a very unique and fine one."

Her travels last week prompted extensive press comment in Canada. The Toronto papers especially picked up on the story and played it on the front page for most of the week.

The Toronto Star, the country's big-gest paper, ran a three-column, front-page picture of Margaret leaving the ballet that showed her wearing a daring dress with a slit up the front. The Toronto Sun, a racy tabloid, asked, "Where's Maggie?" in a screaming front-page headline before she resurfaced in New York. Afterward, the Sun ran an editorial titiled "C'mon, Maggie," which declared: "Someone should control the lady. It is not only reprehensible, it is unacceptable for the wife of the prime minister to be cavorting with a group like the Rolling Stones." (The Sun was particularly upset because one week before the Stones' concerts, lead guitarist Keith Richard was arrested in Toronto and charged with possession of heroin for the purposes of trafficking.) A Sun cartoon showed Margaret rolling off a cliff on a stone.

But the most sensational press on Mrs. Trudeau was abroad. In particular, there were suggestions she was having an affair with one of the Stones, although she emphatically denied it. In the New York Daily News, "Suzy" wrote suggestively: "Ron Wood . . . is Mrs. Trudeau's very special Stone - and you can roll with that one. Ron is at the Plaza Hotel in New York. He can probably tell you more about where Margaret is staying than maybe even the prime minister."

In London, where sensationalist journalism was invented, the tabloids could barely restrain themselves. The Daily Mirror blared on its front page: "Premier's (sic) Wife in Stones Scandal." Inside, the headlines read: "Premier (sic) Trudeau Plays It Cool Back Home as his Wife's Liberated ANtics with Mick Jagger and Co. Rock the Nation," and "The First Lady Who Got Turned On by the Stones." The Daily Mail shouted: "Canada's First Lady Shocks the World and Trudeau Orders His Wife: Come Back Now."

The news even reached Nairobi, where a newspaper imagined Mrs. Trudeau, clad only in a nightgown, fleeing down a hotel corridor while being chased by Stones.

The whole spectacle might have come as an opportunity for vicarious escape for many in Canada, a country with few real celebrities. Canadians have, after all, become used to Margaret Trudeau's unconventional conduct. She was virtual flower child fresh out of university when she married Trudeau in 1971. She stayed out of the public eye at first, then hurled herself into the 1974 election campaign, telling one audience that Trudeau was a loving man who had taught her a lot about love.

Last year she broke into song at an official reception for the Trudeaus in Venezeula. She wrote the song herself in tribute to Blanca Rodriguez dePerez, wife of the president of Venezuela. When she returned home to criticsm, she called in to hot-line radio shows to attack her critics.

She also caused ripples of comment at a White House state dinner last month when she wore a knee-length white dress for a function at which floor-length attire is the norm for women.

Trudeau himself joked about the publicity Margaret received the past week. He told a press conference that Margaret's private life was her own affair and added: "So a lady goes to a rock concert and then goes to New York to visit her friends and to do some photography. I don't think she can be faulted for disappointing the Canadian people or rocking the Canadian dollar."

The next day, while speaking to a group of college students, Trudeau heard a baby crying in the audience. "Is my wife out there?" He quipped to general laughter.

The only person who seemed outwardly concerned about Margaret's behavior was her mother, Doris Sinclair. Said Mrs. Sinclair: "I hope she's not sick." It was a reminder that Margaret had entered a Montreal hospital for psychiatric treatment after the 1974 election.

But Margaret's behavior could have serious political overtones as well. If, as has been suggested, the marriage breaks up, it could damage Trudeau's reputation in the country. If, on the other hand, the couple stays together, Trudeay might decided to get out of politics to save his marriage.

Trudeau has said in the past that his family life could persuade him to leave politics. "If family circumstances made my job impossible, then I supposed I might have to reconsider my job," he said in an interview last year. "But that's rather hypothetical because, if anything, Margaret has shown that she has a pretty great ability to adjust," that was 10 months ago.