In the words of the German poet Rainer Maria Rilke it appears that ‘for one human being to love another is the most difficult of all tasks’, and this is true for parents and children, friend and friend, lover and lover and husband and wife. For the purposes of Valentine’s Day I am going to focus on adult relationships. In the USA, 60 per cent of marriages breakdown and, poignantly and significantly, 80 per cent of second marriages end unhappily. Those statistics do not take into account the high percentage of intact unhappy marriages. It is a real conundrum that if, on the one hand, love is the greatest power on earth – the force that sustains human life – how, on the other hand, is it that many relationships are a near-certain prescription for unbelievable pain and emotional devastation?