All sustained relationships depend to some extent on forgiveness. People hurt each other no matter how much love they share, and it's a truism that the greatest hurts are meted out by the closest of intimates. No friendship, no marriage, no family connections of any kind would last if the silent reparative force of forgiveness were not working almost constantly to counteract the corrosive effects of resentment and bitterness. Without forgiveness there could be no allowance for human frailty. We would keep moving on, searching for perfect connections with mythical partners who would never hurt or disappoint. The wish to repair a wounded relationship, whether it takes the form of forgiveness, apology, or some other bridging gesture, is a basic human impulse. The need to forgive may be as strong as the need to be forgiven.

When we think about forgiveness, we tend to imagine one person deeply and decidedly wronged by another. But in most relationships, so much good and bad is going back and forth that it is not always clear who needs to apologize and who needs to forgive. Indeed, in such cases the struggle to forgive and the struggle to apologize are barely distinguishable.

A man, part of a couple I am seeing, complains to me that "my wife has no forgiveness," and he is in agony over it. Six years ago he had an affair. His wife says she has forgiven him, but she still makes him take an AIDS test every six months because, she says, she cannot trust him. She won't acknowledge that she is holding a grudge. Nor has she been able to grasp how her sexual coldness toward him contributed to his straying. The original blow hit her in such a deep place that all her thoughts and feelings stay tightly organized around her wound. And his current behavior—barking, raging, denouncing—when combined with her psychology makes it hard for her to shake feeling like a victim. Unconsciously, she believes that her grudge is her only source of power. Unless she keeps him in purgatory, constantly begging to be let out, she will get crushed again. It is a sadistic solution, one that satisfies both their psychologies in ways they cannot see. He reacts to her withheld love like a panicked child, pleading and dependent, and then retaliates by bullying her mercilessly. And they've been stuck there, going round and round, each a victim, trying to live a married life with an indissoluble wedge between them.

Neither the husband nor the wife is in a position to stop the destructive pattern and freely forgive each other. Too many layers of their psychology stand in the way. This is not to say they don't have choices. They do, and certain of those choices can move them in the direction of forgiveness. They have inner resources they are unaware of, resources that might surprise them. It is just this zone of the possible, where our psychology entraps us and yet also holds the potential to liberate us, that most interests me.

Our capacity to forgive reveals a great deal about our inner lives. It is a measure of our ability to recognize the humanity in someone who has hurt us, as well as to see our own limitations and complicity. It represents the ability to tolerate disappointment in others and accept that they won't always be what we need them to be. And this sensibility applies to our view of ourselves, too, for forgiving others is nothing but the mirror image of forgiving oneself. Forgiveness is not just a by-product of growth: The struggle to forgive can promote growth. Significant acts of forgiveness entail letting go of a precious story we tell about ourselves, risking the awareness of a larger, less self-justifying truth. In struggling to forgive what is most difficult for us to forgive, we reveal our courage, imagination, and potential for growth. Much the same could be said about owning up to the wrongs we do.