Happy Rockefeller is tall and tawny and glows with good health. Her sun-streaked hair looks forever windblown, her legs evenly tanned year-round. She is a member of the nation's richest family. And at 48, she presumably will soon begin a life of even more prominence as the wife of the new Vice-President.

Yet, in her own wholesome way, Happy Rockefeller is also the Dark Lady of American politics, an enigmatic and intensely guarded person who is less than happy about her husband's new job. As Nelson Rockefeller leaped to national attention once again, Happy became even more retiring and vulnerable. "Shy is too simplistic a word," says one close friend. "She is a very private person." Says another: "She doesn't like this at all. But she'll do it because she has to."

No one blames Happy for her aversion to notoriety. Her painful divorce and remarriage to Nelson Rockefeller in 1963 was one of the most sensationally publicized events of the decade. Ever since, she has withdrawn into her own private world, refusing all interviews and leaving the politics to Nelson, while quietly raising their two small boys, Nelson Jr. 10, and Mark, 7.

Born Margaretta Large Fitler on Philadelphia's Main Line (her father inherited $8 million from the family's rope-making business), Happy grew up in a blue-nosed society that advised a girl to get her name in the papers only four times: when you are born, when you make your debut, when you are married, and when you die. Her socially ambitious mother and gadabout father split up when she was 10. Happy's mother, a friend recalls, "was a great beauty, but she was extremely self-centered. She did not have much time for her children." The same friend remembers Happy as "a very pretty, sweet thing, always smiling—but there was a quiet sadness too."

After graduating in 1944 from Bryn Mawr's exclusive Shipley School, where she was remembered as a tomboy honors student, Happy went to work in a hospital for the Women's Volunteer Service. There she met handsome James Slater Murphy, called "Robin" by his friends, an Army Medical Corps captain, a graduate of Princeton. Happy and Dr. Murphy were married in a Rittenhouse Square ceremony that the papers called the season's biggest social event. He was 28; she was 22.

The Murphys moved to New York City and fell into the gravitational field of the Rockefellers. Robin's father had been a world-famous cancer-research scientist at Rockefeller Institute; Robin, who would become an eminent virologist in his own right and a developer of the flu vaccine, also signed on at the Institute. One of Robin's childhood friends was David Rockefeller.

In the early 1950s, the Rockefellers sold Robin and Happy 13 acres of land adjacent to their Pocantico Hills estate near New York City. The Murphys built a house there and began to be invited to the Rockefellers' parties. Robin belonged to the exclusive Knickerbocker Club in Manhattan; so did Nelson. Robin's family had long owned a home in Seal Harbor, Me., across the bay from the Rockefellers. Happy spent every summer there.

In 1958, Happy went to work as a volunteer in Nelson's gubernatorial campaign. After the election, Rockefeller took her to Albany on his payroll as his confidential secretary.

Their romance, played out against the broad canvas of Pocantico Hills, Seal Harbor and Manhattan, eventually became public property. On Nov. 17, 1961, Nelson and his wife, Mary Todhunter Clark, separated, later to divorce. On Apr. 1, 1963, Happy divorced Robin, signing away custody of their four children. On May 4, 1963, she and Nelson were married in Pocantico Hills. An unsympathetic public saw Rockefeller as a man who had cast aside his wife of 31 years and broken up two families in order to marry a 36-year-old woman, 18 years his junior. Happy was seen as a heartless mother. Even the minister who performed the wedding ceremony was rebuked by his superiors.

Happy's reputation as a femme fatale did not last long. She gamely joined in Rockefeller's campaigns and won over crowds with her cheery, unaffected ways. Yet she never fully entered into the cigar-and-spittoon life at the Albany statehouse, preferring to make a home in the Pocantico Hills compound (35-room mansion, four tennis courts, two swimming pools, two squash courts and a nine-hole golf course). There she practiced the vigorous life and occasionally got Rocky to do the same—golfing, riding and playing excellent tennis.

When Rockefeller announced his decision last December to step down after nearly four terms as New York's governor, Happy was clearly overjoyed. This summer she and Nelson have been leading the life of ordinary millionaire folk at Seal Harbor, building bonfires and roasting lobsters on the shore. Rocky tools around town in his 1931 Model A Ford; Happy, a casual dresser who rarely wears makeup or jewelry, picks up groceries in their 1968 Mustang. They watched President Ford's swearing-in on an antiquated black-and-white TV set in their bedroom. Happy's serious project this summer is plowing through an anthology of American poetry.

Even the arrival in Seal Harbor of a swarm of journalists in recent weeks hasn't upset the routine much. When a couple of reporters couldn't find rooms at local inns, Happy arranged to let them sleep in the garage, even offering to run down with sheets and make up the beds herself. Still, she tries to avoid substantive talk with journalists. One ground rule during a recent press conference was that her husband would answer all questions—even those directed toward her. "She's afraid she'll make a misstep," a friend says. "I've seen her turn to Nelson and say, 'What should I say—what should I do?' The trouble is, she doesn't know her own charm. On her own she comes off beautifully."

Rockefeller himself says that he seeks out Happy's advice on political questions. Their friends agree that her contribution to the marriage goes far beyond her expert handling of the sails while he steers their sloop. "She makes you feel immediately at home," says a friend, Mrs. Thomas Braden, wife of the Washington political columnist. "He relies on her intuition and judgment. People tend to unburden themselves to her. People often feel closer to him because of Happy."

Inevitably perhaps, given the history of their romance, rumors of trouble in their marriage have surfaced in the past couple of years. Says a family friend of Nelson: "There are always dozens of women who think he's interested because he has the same charisma as the Kennedys, and he makes each woman he meets feel as if she's special. So many of them are so silly and get the wrong idea and misunderstand. There's no one in his life other than Happy." Mrs. Braden concurs: "There are no other women. I would know."

When Rocky got the call from the White House about the vice-presidency, he talked first to Happy—"and nobody else"—taking her for a long walk in the woods. "Happy's been absolutely marvelous about this business of being in public office," says Rocky. "Let's face it, it has some very limiting factors." Adds a more tentative Happy: "As a concerned citizen, I'm thrilled. Personally, it's the beginning of a new adventure."

One indication of how much Happy prizes her family and her privacy came when she went to Washington to see President and Mrs. Ford. After a quick lunch with Betty Ford, Happy passed up a White House dinner that her husband attended that night. Instead she flew back to Seal Harbor. The reason: Nelson Jr. was playing in his first tennis tournament. With his mother sitting proudly in the stands, he won.