‘Falling in love’ is one of the deepest emotional experiences of a person’s life. Indeed, it is so important to us that much of our great literature, our most-liked films and our enduring works of art express our universal preoccupation with it; not to mention almost every pop song ever written. And yet the power that this state holds, especially when it occurs for the first time, has been one of life’s great mysteries. We haven’t been able to explain why we ‘fall in love’ or even what ‘falling in love’ really means! We haven’t been able to explain the heart-pounding, over-the-moon, walking-on-air, footloose-and-fancy-free, dancing-in-the-streets, crazy-happy feelings of ‘falling in love’, which can be so overwhelming that everything else ceases to matter; and we haven’t been able explain its dark flipside either, which is that the loss of love can lead to unbearable pain and heartbreak. What is the reason for the intensity of the feelings and this sense of longing we have when we ‘fall in love’?