"When these cycles hit these moments, you have to have a new glue. You have to re-create a new baby," she said, adding that without a common mission or purpose, couples stumble as they enter into the next stage of their lives.
Others have remarked on the irony of the Clinton marriage outlasting the Gores', but Brooks said she is not surprised.
"[The Clintons] have really quite a common vision, a partnership," she said. "They have a political baby."
Coontz said the Gores' decision to separate can be seen through a positive lens.
"They've been together for 40 years," she said. "They worked together through tremendous challenges, raised their kids, and they grew apart. It's too bad they grew apart."
But, she added, "It's a success that they have the option to move on and not be stuck."
When the Gores married, in 1970, most women did not work outside the home. And in the majority of states, men maintained the legal right to make decisions regarding community property, where the couple would live and other major decisions that modern couples expect to be share as equals, Coontz said. Women were still expected to defer to men, whether in or out of marriage.
Now, said Coontz, "We have higher expectations." And more complications, as both partners look to pursue their own ambitions.
"Relationships need more tending than they did in the past," she said.
Solomon said she agrees. If given the chance, she said, she'd have offered the Gores this advice, "If you are in a place where you're doing something that you're excited about, make sure your partner gets a lot of affirmation. Make sure your partner knows that they're a very important part of your life, of what you're doing, that they're valuable."