If ever an expression defined human behavior, it is the notion that the grass is greener on the other side of the fence. Ovid, an ancient Roman philosopher and poet was perhaps the first when he said that “the harvest is always more fruitful in another man’s fields.” This sense that life is better for others has perhaps its strongest and most debilitating hold on us as it affects our relationships. Infidelity, the most cutting breach of trust that we experience in our intimate relationships is rampant. It is so common that not having some form of the experience is uncommon. While the stories of infidelity are as unique as the millions of people who engage in them – our shared human biology, emotional needs and the thinking errors that allow them – are universal.