In one of Anthony Trollope's late romantic novels, The Duke's Children, the Duke of Omnium finds that both his children seek to marry for love. For 800 pages he seeks to frustrate them. “What am I to say, Sir?” asks his son, the Earl of Silverbridge, in despair. “I love the girl better than my life. What is a man to do when he feels like that?” Lady Mary Palliser tells her father that she loves Frank Tregear, a man without rank or money, more than anyone else in the world. “Then you must conquer your love!” the Duke replies. “It is disgraceful and it must be conquered!” But can it be?

Love, WH Auden pointed out about Romeo & Juliet, is at its most powerful when it is frustrated. But even at its most powerful, can love bear the burden that the 20th and 21st centuries have placed on it – the burden of delivering the highest levels of human happiness?