The nature of royal weddings as very public declarations of love can cause us to reflect on love and partnership – and on 29th April 2011 when Prince William and Kate Middleton tied the knot, the royal couple took a vow that declared a commitment to love and cherish ‘til death do us part’. But what is ‘love’? What is it that makes us fall in love with someone and can we put a meaning on it? We’ve all experienced love, whether it is a friend, partner, family member, or a pet – but these are all very different kinds of love. So how do we define love when it encompasses such a variety of emotions? Carolyn Price, senior lecturer in Philosophy, and Timothy Chappell, director of the Ethics Centre, at The Open University, discuss the nature of love, from love as a function, to ‘the Doppelganger problem’ – should we also love another person with the same traits and qualities as the person we already love? Finally, the notion of love as a duty within marriage is explored.