Cheating (Hannes Hepp, Getty Images / October 4, 2013)

Melissa Richman, a psychologist and social worker based in Los Angeles, reminds couples that monogamy is difficult and that "a committed relationship is a friendship, and there's a journey in there."

But while she urges forgiveness, she also bemoans a society in which people assume they should always get what they want.

Sometimes relationships, in marriage or outside it, shouldn't be salvaged post-cheating. A long-term affair that involved many years of deceit can stink of such disrespect that it's hard to bounce back, Haltzman said. He also cautions against returning to cheaters who have serial affairs or continue to see other people as the primary relationship grows closer.

But if the cheating partner is willing to offer complete transparency and work hard to earn back trust, it can be worth giving it another shot.

Victoria, 52, is trying to rebuild her relationship after she found out that her boyfriend of five years had been having an ongoing affair for three years.

"What is making me want to try is his actions, his tears," said Victoria, who asked that her last name and location not be used. "Things have come out during therapy: his inability to communicate and how he felt in the relationship, as though I wasn't committed to him."

The fallout from the cheating, which took place during his lunch hour with a woman he met online, was devastating.

"During one of our discussions, I got up and took every picture of us in our house and smashed them on the ground," Victoria said.

Couples and individual therapy have helped her and her boyfriend identify the underlying problems that led him to stray — including, ironically, her reluctance to get married, which left him feeling insecure, she said. His eagerness to address his issues, reveal any detail she requests and do anything it takes to make her feel safe, plus her examination of her own behaviors that might have left him feeling disconnected and lonely, have made Victoria optimistic that they can get through it.

It worked out differently for Carol and her former fiance in Florida.

She said she forgave her fiance's vacation romance too easily at first because she couldn't let the relationship go. But, she said, when she found hints that he was continuing to see other women, she felt herself become unhinged. She said she broke up with him but would obsessively check his new girlfriend's social media accounts. A few confrontations led him to pursue a restraining order against her, she added. Acrimony over money led to their house going into foreclosure, and she declared bankruptcy.

More than two years later, Carol feels she dodged a bullet but was scarred.

"I tell people I wasn't married," she said, "but I got divorced."

Before you decide

Rather than rush to save or end a relationship after discovering infidelity, couples should take time to understand why it happened and ask What is it about this person that is good for me? Clinical psychologist Janis Abrahms Spring, author of "After the Affair" (William Morrow), offers tips for rebuilding a relationship.

Write apology letters. After the hurt partner "talks about their hurt with an open heart," the cheating partner should write a letter spelling out exactly what he or she is sorry for. And vice versa. Letters are important because they demand more thought, and often people want to read the words over and over.

Engage in trust-building behaviors. That could mean the cheating partner hands over cellphone records or promises to reveal immediately if the affair partner gets in touch. "Trust and forgiveness are not gifts from the hurt partner," Spring said. "They must be earned."

Filter the discussion. It's tempting to ask for every gory detail, but consider if that's helpful, or reframe the question to be about the couple rather than the third party. Be careful not to go on and on, which can alienate the unfaithful partner and deter conversation. The best way to communicate is to speak genuinely, honestly and briefly, with the listener mirroring back what was said, so he or she feels heard.