Countless couples complain of losing the “spark” in their relationship. Some chalk it up to evolved differences, a slow growing apart, or sheer familiarity. The wave of “deadness” that can submerge a relationship after the first thrilling months or years has caused many couples to lose hope, and even look elsewhere for the excitement of newfound intimacy. With researchers estimating that 30-60 percent of married individuals in the United States will have an affair at some point in their relationship, it may be time to really examine what causes our affections to wane. What prompts the shift from helpless love to deep disinterest? What turns our heart-racing enthusiasm for another person to boredom and dissatisfaction?