“It’s not our place to tell anyone to forgive or not to forgive,” Dr. Lerner said in an interview. She disputes popular thinking that failing to forgive is bad for one’s health and can lead to a life mired in bitterness and hate.

“There is no one path to healing,” she said. “There are many roads to letting go of corrosive emotions without forgiving, like therapy, meditation, medication, even swimming.”

Hardest of all, Dr. Lerner said, is to forgive a nonapologetic offender, like my aunt whom I had loved dearly and who served as my second mother after mine died. But when I, raised Jewish, married a Christian, she refused to come to the wedding and never apologized for the intense hurt her absence had caused. Although I made several attempts to restore the relationship, she always managed to deflect them, and to this day, more than half a century later, I cannot forgive her.

The focus of an apology should be on what the offender has said or done, not on the person’s reaction to it. Saying “I’m sorry you feel that way” shifts the focus away from the person who is supposedly apologizing and turns “I’m sorry” into “I’m not really sorry at all,” the psychologist wrote.

As to why many people find it hard to offer a sincere, unfettered apology, Dr. Lerner pointed out that “humans are hard-wired for defensiveness. It’s very difficult to take direct, unequivocal responsibility for our hurtful actions. It takes a great deal of maturity to put a relationship or another person before our need to be right.”

Offering an apology is an admission of guilt that admittedly leaves people vulnerable. There’s no guarantee as to how it will be received. It is the prerogative of the injured party to reject an apology, even when sincerely offered. The person may feel the offense was so enormous — for example, having been sexually abused by a parent — that it is impossible to accept a mea culpa offered by the abusive parent years later.

Righting a perceived wrong can be especially challenging when it involves family members, who may be inclined to cite history — he was abused by his father, or she was raised by a distant mother — as an excuse for hurtful behavior. “History can be used as an explanation, not an excuse,” the psychologist said. “It should involve a conversation that allows the hurt party to express anger and pain if an apology, however sincere, is to heal a broken connection.”