Editor's note: Joshua Coleman is co-chairman of the Council on Contemporary Families, a nonprofit organization that gathers research on American families, and a psychologist. His most recent book is "When Parents Hurt: Compassionate Strategies When You and Your Grown Child Don't Get Along."
(CNN) -- When faced with a barrage of information about a marriage that has collapsed publicly, like that of Arnold Schwarzenegger and Maria Shriver, it's easy to preach about what we would or wouldn't do in such a situation, or what somebody else should or shouldn't do.
The reality is that, as with so much in life, we don't know what we'd do if it happened to us. And we're in no position to judge another person's marriage.
When Hillary Clinton had to go through the public humiliation of her husband's affairs, the common wisdom appeared to be that she was a patsy to stay with him -- or stayed only to ensure her political future.
Perhaps one of those views is true. There are many reasons why people stay in marriages they might otherwise leave. It may also be that she loved her husband or her daughter enough to endure her family's humiliation, and is glad that she did.
Regardless of reasons, there are several important ingredients necessary to heal a serious betrayal in marriage.
One of the most critical factors is that the person who lied, cheated or betrayed has to want to change, be able to change and be willing to withstand the guilt, remorse and shame evoked by witnessing the suffering brought on by the behavior. The person also has to know that this is a process that will take a few years, not a few months, to heal.
Affairs, particularly those involving the revelation of a child fathered outside the marriage, remove the veil of trust that we all need to function in life, to place confidence in our perceptions and to be vulnerable. That trust isn't quickly replaced.
Betrayed partners must also be driven by some powerful motivation to forgive or consider forgiving the cheating partner, such as still believing in the partner despite the enormity of the hurt, or not wanting to put themselves or their children through a divorce.
In my clinical work, I have been impressed by some people's ability to very clearly set limits and walk away from a marriage in which the other person was either unwilling or incapable of change. I could easily imagine Shriver saying that her husband's actions are beyond forgivable.
I have also been impressed by the strength of some to stand up for their marriage, despite feeling deeply hurt or betrayed, and have seen their spouse benefit from that commitment and modeling of love, dedication and courage.
Assuming the partner is worth forgiving, or worth the consideration of forgiving, the betrayed partner has to have the psychological reserves to do so.
And not everyone does. People who have experienced a series of betrayals in their lives, such as those who were profoundly rejected or neglected as children, sometimes don't have the resilience to see their partner as a flawed, though potentially redeemable, human being. For them, an affair or other serious betrayal sounds an alarm that brings forth a cascade of painful childhood memories of helplessness and hopelessness or feelings of unlovability.
For such a person, learning to love and to trust a spouse enough to get married was a psychological achievement all by itself -- a triumph of love over fear; a feat built on a foundation that required an ongoing effort to address the constant welling up of childhood memories warning against the folly of trust.
Part of what's tricky for parents whose marriages have been rocked in this way is finding the ability to separate out a healthy need to protect oneself from a partner who may well be too selfish or self-destructive to remain close to, and the desire to protect the children from that parent's character flaws.
Yet many people are terrible spouses but decent parents. Barring a history of parental abuse or severe neglect, a parent should let her children discover the other parent's flaws for themselves.
And there is another child's well-being that everyone should consider: the son that Schwarzenegger fathered with their family's housekeeper.
When Shriver was campaigning for her husband in 2003, she described him in the following way: "He's honest, he's sensitive, he's sincere. And he is gracious with every bone in his body."
Let's hope that she is still able to find those qualities in her husband. While she'll never forget, she may be able to eventually forgive him, which is better for her serenity -- and for all of the children, who still need their father.
The opinions expressed in this commentary are solely those of Joshua Coleman.