A study of Greek married couples suggests there is some truth in the proverbial seven-year itch, revealing that at least half of men, and six out of 10 women have been unfaithful by their seventh anniversary. For some, the itch begins much earlier, according to the survey by the Society for the Study of Human Sexuality (EMAS) with a sample of 18,000 couples. Nearly one-third (29.5 percent) of men and 2 percent of women claim to have strayed after two years of marriage. After seven years, 56 percent of men and 64.5 percent of women report having had sex with a new partner. Waning desire – for men and women – occurs for various reasons, said EMAS president Constantinos Constantinidis. The hormones that drive men and women to chase, or be chased, diminish during the course of a relationship, according to experts, who say routine also mutes sexual urges.