If you are an old-fashioned romantic, true love has a nice ring to it. Our films, novels, poems, and music are all steeped in the notion, with characteristics that include unwavering fondness and even selfless devotion. But does it actually exist, driven by our biological underpinnings? Or is it a myth that harms what could be a more realistic, and thus healthy, expectation of relationships? As American marriages teeter at historic lows, and attitudes shift, it is a growing question among both the single and the attached.