Even when there's no sex involved, the pain of infidelity can be real.
Love is one of the most profound emotions known to human beings. There are many kinds of love, but most people seek its expression in a romantic relationship with a compatible partner. For some, romantic relationships are the most meaningful element of life, providing a source of deep fulfillment.
At least for humans, this most basic of acts is anything but basic. As the pioneering sex researcher Alfred Kinsey put it, the only universal in human sexuality is variability itself. Within the universe of intimacy and pleasure that sex affords, however, there's a lot of room for error.