Quotes of the Day

Each marriage is its own little ecosystem. When breakdown occurs, it's impossible to discern from the outside the exact chain of events that led to systemic failure. This is especially true of high-wattage marriages like the 25-year union of Arnold Schwarzenegger and Maria Shriver, which have pressures — from politics and showbiz — most partnerships don't have.

But while each one is unique, most marriages, like most systems, occasionally display similar patterns. TIME.com asked some well-respected therapists to weigh in on what those patterns might be, and what regular people can learn from the Arnold-Maria split.

(More on TIME.com: See pictures of Maria Shriver's career.)

Several therapists pointed to recent stresses in Shriver's life. "It's often, in my experience, the loss of and grieving for significant family members, like a parent, that destabilize a couple's relationship," says therapist Barry Ginsberg. "This is difficult to reconcile without help." (Sargent Shriver, Maria's father, died in January after a long illness. Her mother Eunice passed away in 2009.)

This is particularly true for wives, says Steve Stosny, therapist and author of Love Without Hurt. "The husband typically withdraws from the grieving or ailing wife, making her feel isolated in a time of vulnerability," he says. "Once she recovers on her own, she sees no point to the relationship where the man has just proven to her that he won't be there for her when she most needs him."

As a rule, men prefer to deal with stress differently, in isolation. Sharing it makes them feel inadequate as protectors, as, says Stosny, does a wife's long-term grief. "Men in general cannot bear to see their wives distressed or depressed, especially when it goes on for a while," he says. "They can handle short-term, acute problems where they can respond like heroes, but over the long haul, they are not so good at nursing."

(More on TIME.com: See the top 10 most shocking celebrity-relationship flameouts.)

Other therapists speculate that the origins of the cleft may have arisen much earlier. "It looks to me like it's about a lot of unresolved issues from their past," says Sharon Rivkin, a therapist who specializes in marital conflict resolution. "People think they're fighting about one issue, but they're really fighting about something entirely different." Rivkin suggests their political differences may have been one point of conflict.

Others wonder whether politics really had anything to do with it. "It is a marital myth that common interests or beliefs keep marriages together," says relationship coach Mimi Daniel. "Success in marriage is allowing and encouraging each individual to be the best they can be while still being part of a partnership. "

But it's possible that with the pressures of political and public life and the sheer time commitment of being the first couple of California, the Schwarzenegger-Shrivers put a lot of conflict-resolution on hold. "I think what people could take away from this is to always deal with their issues as quickly as possible," says Rivkin. "No one is immune to marital problems and [people] should get help as soon as they see the first signs of a problem. "

(More on TIME.com: See five reasons to get (or stay) married this year.)

Psychiatrist Scott Haltzman notes that 25 years is a pretty long time to stay married. For much of human history, people rarely even lived long enough to see that anniversary, so in many ways, it's new ground. "Staying married past this landmark is a special challenge," says Haltzman, "made even harder in a society that holds out the promise of so many options, and drives home the message that 'you deserve your happiness.'"

Like many of the therapists who spoke with TIME.com, Haltzman believes a reconciliation between Schwarzenegger and Shriver is possible. "Practically every couple can look back at the totality of their marriage and say it was drifting apart for a long time or that there were signs that it wasn't going to be forever. That's the norm."

But couples who stay together do not use that data to base their decision to divorce. "Longstanding marriages are composed of individuals who go through these rough times, but consider options other than divorce," says Haltzman. "When they stay with the relationship, they actually grow stronger."

(More on TIME.com: See TIME's 10 Questions for Maria Shriver.)

Since divorce is almost always more expensive than people imagine it will be — particularly in the community property state of California — that's probably helpful advice. It might also explain the surprising longevity of the union of Bill and Hillary Clinton.

• Belinda Luscombe