Absolutely yes, couples can and do get over infidelity. Not only can they overcome it so that it no longer has a significant negative impact on their relationship, but they can use it to spur them to work on their relationship and, in so doing, make their LTLR stronger and happier than it ever was before.
That isn't to say that the infidelity will ever be forgotten or become insignificant. We tell the couples we work with that even though they can move past it, the infidelity will always be a fact of their lives, just like their wedding date, the birth of their children and health crises. It will be a reference point like the other benchmarks. Many couples make the mistake of believing or assuming that when they "get over" the infidelity it no longer becomes important to discuss or reference. This is not necessarily the case. Over time the way the betrayal is referred to will likely change. It will become less "charged" with negativity, but will always be a turning point. We tell couples that this turning point is also another growth point in their relationship. It was not a mature, healthy way of dealing with a crossroad, but they can take all the credit for using it to grow and improve both individually and as a couple.
The author of Intimacy after Infidelity: How to Rebuild and Affair-Proof Your Marriage (2007, New Harbinger Publications), Dr. Solomon received his undergraduate degree at Dartmouth College and his M.A. and Ph.D. in Clinical Psychology at the California School of Professional Psychology (Los Angeles). He has been in private practice in San Diego and La Jolla, California for more than 20 years.