We've all heard the adage: "Once a cheater, always a cheater." If your partner has been unfaithful, you're likely getting all sorts of advice from well-meaning friends and family.Much of that advice may involve ending your relationship. Yet it's possible -- and perhaps even beneficial -- to stay in a marriage or long-term relationship when one partner cheats. That's the idea of two new books from noted experts on the topic: a newly revised edition of the best-selling "After the Affair" by Janis Abrahms Spring and "The New Monogamy: Redefining Your Relationship After Infidelity" by Tammy Nelson.But should you really forgive and move on after infidelity?"Most of us are totally unprepared for what lies ahead in a relationship, and ignorant of what's required to last the course," Spring writes. "An affair shocks us into reality. Fortunately, it also invites us to try again."Adds Nelson, "Many couples instinctively know that infidelity is much more complicated than our culture sometimes admits."Couples can, and do, often find their way to an ultimately deeper, more intimate bond -- but it can take time and effort."In the wake of infidelity, most betrayed partners feel surprised and caught off guard," says marriage and family therapist James Walkup. "But even though the hurt person may have assumed they would not stay married to a straying spouse, they may realize they still love their partner and want to work on the relationship."Today, not all committed relationships follow the traditional definition of monogamy. For example, both partners may decide together what constitutes cheating going forward -- whether that means flirting with a particular friend, visiting a strip club or even having sex outside the relationship."I have seen a growing number (of) straight and same-sex couples thrive on the infamous 'monogamish' agreement," psychotherapist Jean Malpas says. "They realize that long-term relationships might need to include the reality of attractions to other people. They carefully define trust and craft guidelines for acceptable behavior based on their level of comfort with risk and fluidity."Such a "monogamish" approach tends to be more common among gays, lesbians, bisexuals and transgendered people, notes sex therapist Margie Nichols. "The issue is commonly on the table for consideration or discussion when LGBTQ partners get together, and when a transgression is purely sexual (as opposed to emotional), it may be less likely to end the relationship," she says.That's not to say that monogamish couples are safe from infidelity, however. "Just because a couple is monogamish does not mean that they will be any more forgiving of a partner who breaks the rules and violates their trust," says social psychologist Justin Lehmiller. "Deciding whether to work things out has less to do with the gender of the partners and more to do with whether it was a good quality relationship to begin with."Nelson adds, "Ideally, your relationship will continue to grow and change as each of you grows and changes, and it may change position on the (monogamy) continuum throughout the years."You can't heal from infidelity overnight. Instead, take time to rebuild your relationship slowly. Rather than ignoring the affair, be willing to share your pain, listen to each other and provide comfort when one partner is remembering the betrayal -- all can help lessen the pain while re-creating the original bond that joined the two of you together."Turning your back on a damaged relationship may be the simplest or most sensible solution, one that frees you from the tyranny of hope," Spring writes. "But it also may be a way to escape growing up, facing bitter truths about life, love and yourself, and assuming the terrible responsibility for making your relationship work."Some couples undoubtedly view an infidelity as the end of their relationship -- and in some cases, going your separate ways may be the best decision. But for partners who are willing to recommit themselves to each other, an affair can be a turning point."Sometimes my clients acknowledge that coping with infidelity was the worst and yet the best thing to happen to their relationship," Walkup says. "The distance between them has been bridged, and a deeper level of sharing and intimacy can bring joy and hope in the long run."