In 1982, they divorced at her request, according to Edward Klein, author of "Ted Kennedy: The Dream That Never Died." It was "a real effort on her part to establish herself as an independent woman who would no longer be an extension of Ted's life. She tried very, very hard," he told USA Today.
By 1991, the senator met Victoria Anne Reggie, who has been credited with helping Kennedy stop drinking and carousing.
"After the divorce [Joan and Ted] were still close and spent Thanksgivings together at the compound," said the family member. "She knows his wife Vicki. It's not really a relationship, but they are civil to each other and not a couple of icebergs passing in the night."
Joan Kennedy still maintains her Beacon Hill address, but summers in Hyannis Port, where locals guard her privacy.
"People are very protective of her," said Barbara Blume, who volunteers at the John F. Kennedy Hyannis Museum.
"She didn't know that she would have to take that on when she married Ted," Blume told ABCNews.com. "She was a very private person and then was thrust into the limelight. The Kennedys weren't the best of husbands."
"She learned from Jackie how to be a political wife," said Blume. "She (Joan) had to share Ted -- not only with her children -- but with Bobby's children and John's children because he was the father figure."
Visitors to the museum often ask if Joan Kennedy is still alive or how the couple, as "good Catholics" could have been divorced, according to Blume.
But most locals regard Joan Kennedy kindly.
"I think in Massachusetts and Boston especially, they understand alcohol problems and they understand the Kennedys and are very forgiving," she said.
"She did the best she could with her life," said Kay Faulkner of neighboring Yarmouth. "It's awfully hard to have her personal problems -- alcoholism -- in the limelight."
But according to one longtime Hyannis Port resident, many say privately that Joan Kennedy "humiliated" herself and her family and "made a fool" of the Kennedy name.
"Yet," she said. "People still care about her."
ABC Information Specialist Gerard Middleton contributed to this report.