June 2, 2010— -- The surprising divorce announcement from Al and Tipper Gore has saddened people who know them, but friends and experts say there were subtle cracks in their marriage that were easy to miss.
Together, the two had weathered the near-death of their son in a 1989 car accident, Gore's vice-presidency, his loss of the presidency to Florida's notorious chad ballots, and then his reinvention as an environmental crusader.
But as their marriage passed the 40-year mark, their paths and expectations diverged, former Gore campaign manager Tony Coelho said.
"She went and did her thing," he said of Tipper Gore. "She was supportive, but she didn't share the world stage with him."
ABC News Analyst Cokie Roberts told "Good Morning America" today that the couple's announcement Tuesday caught her off guard.
"It's sad," she said. "These are nice people."
Roberts said she believes that the marriage's perserverance through the more difficult years gave the Gores a common goal that may have dissipated when life began to slow down.
"Is there another shoe to drop?" she asked. "Who knows."
Tipper Gore, once a very public figure herself, has increasingly kept out of public life, leading some to wonder if that difference caused a rift.
Though Al Gore's reinvention as a Nobel Peace Prize-winning environmentalist has led to many accolades, Roberts said, he eventually has to come home where "his wife knows he puts his pants on one leg at a time."
"It's much more fun to be a God than a person," she said.
Family therapist Terry Real told "Good Morning America" today that there may not be one smoking gun that ended the Gore's marriage.
He agreed with Roberts' assessment that the simple act of growing old together may have forced them apart.
"I think the moral of this story … is that nobody knows the inside of a marriage," he said. "People do grow apart."
"I think there have probably been fault lines in the marriage that have not shown in public," he said.