It’s difficult to know for sure how many marriages fail after infidelity, explains Dr. Manly, because “no concrete figure is available given that many divorced couples do not cite a reason for divorce.” However, according to current research, “somewhere between 20 percent to 40 percent of marriages fail as a direct result of infidelity,” she says. “In working with couples where infidelity has occurred, it is clear that betrayals of this nature often lead to deep trust issues that are extremely difficult to heal.” “The work required to heal the relationship [might] be too much for the couple to handle,” explains Alisha Sweyd, licensed marriage and family therapist in Pacific Grove, California. “This could be due to work schedules, family situations, or that the hurt goes much much deeper than just the indiscretion.”  That said, infidelity doesn’t have to end a marriage. “A large [number] of couples make it through an event of infidelity,” says McNeill. “Many couples find they can get a fresh start on their relationship if they are able to work through the issues that made one partner feel like getting their needs met elsewhere.”  “When the partner who strayed is able to identify the triggers that got them to the position of feeling like infidelity was an option and can simultaneously express genuine remorse and attunement with their partner’s pain,” she continues, “many relationships can weather the affair. However, to get there, most need the help of a well-trained relationship therapist. “By working through the issues with an objective therapist, couples stand the best chance of healing the issues that lead to—and resulted from—the infidelity,” says Dr. Manly. “Without professional support, the intricate web of fears, mistrust, and resentment can be exceedingly difficult to untangle and heal.”