Gore spokeswoman Kalee Kreider confirmed the statement came from the Gores, but declined to comment further.
The Gores were telling friends they "grew apart" after 40 years of marriage and there was no affair involved, according to two longtime close associates and family friends, who spoke on the condition of anonymity because it was a personal matter.
The associates said the Gores, over time, had carved out separate lives, with the former vice president on the road frequently. One of the associates said: "Their lives had gotten more and more separated."
Al Gore lost the 2000 presidential election to Republican George W. Bush. He has since campaigned worldwide to draw attention to climate change, which in 2007 led to a Nobel Peace Prize and an Oscar for the documentary "An Inconvenient Truth."
The Gores, who were married on May 19, 1970, at the National Cathedral in Washington, crafted an image as a happily married couple during his eight-year stint as vice president in the 1990s and a presidential candidate in 2000. The couple famously exchanged a long kiss during the 2000 Democratic presidential convention.
The image of their warm relationship stood in sharp contrast to the Clinton marriage rocked by Bill Clinton's affair with White House intern Monica Lewinsky, a scandal that hung over Gore's own presidential campaign.
Al Gore at the time said his wife was "someone I've loved with my whole heart since the night of my high school senior prom."
In a speech to the 2004 Democratic convention, Gore said he wanted to thank "with all my heart my children and grandchildren, and especially my beloved partner in life, Tipper."
Tipper said in a 2000 campaign interview with The Associated Press that Al once gave her a Weedeater for her birthday but had learned to be more sensitive over the years and cared about what she wanted.
"He's very much a gentleman you know, with me around the house," Tipper said. "I know he's dog tired and he could be sitting down and doing something and I need something across the room, he'll get up and get it."
On Halloween, Al and Tipper Gore would dress up in costume and greet trick-or-treaters who made their way to the vice president's mansion. One year, she was dressed as a puppy and he was dressed as Underdog.
Tipper Gore was a co-founder in 1985 of the Parents Music Resource Center, which pushed for parental warning labels on music with violent or sexually explicit lyrics. The group drew the ire of musicians ranging from Dee Snider of Twisted Sister to Frank Zappa, who said warning labels were unnecessary and a danger to freedom.
Tipper Gore later became friends with the late Zappa's wife, Gail, and played drums and sang backup on daughter Diva Zappa's album in 1999.
The Gores have four adult children, Karenna, Kristin, Sarah and Albert III.
In a letter written to then-girlfriend Tipper as a 17-year-old college freshman, Al Gore wrote: "Mother's having a fit about me riding the motorcycle back to Harvard. Dad's mad at my long hair."
Gore later held his father's former seats in the U.S. House and Senate for 16 years. He first ran for president in 1988 at age 39, but drew little support outside the South.
A subsequent bid in 1992 was derailed after the Gores' 6-year-old son almost died after being hit by a car in 1989.
"It was a very spiritual time for both of us," Tipper Gore later wrote. "In Al's case, he decided to write a book and not to run for president in 1992."
The book was "Earth in the Balance," and Al Gore ended up in the thick of the 1992 campaign anyway -- as Bill Clinton's running mate.
Tipper Gore, who has acknowledged treatment for depression after Albert III's accident, is a vocal advocate on mental health issues.