1745, Versailles France.

Jeanne-Antoinette is the King's chief mistress and will now be known as Madame de Pompadour and resided in court with the King.

At this point, the King has been married for 20 years. He married for reasons of state and had mistresses on the side. It was accepted that there is an imperfect fit between marriage and love. Marriage was for children and continuity. Love was for excitement and drama.

In 1812, Scotland. Harriet married John Lambton, the first Earl of Durham, despite the families trying to intervene. John has land and responsibilities, and Harriet is a pretty but illegitimate daughter of the Earl of Cholmondeley with no money and little social status.

The modern couple believed that love should come first and practical considerations second. They are exemplars of the new philosophy of romanticism which prioritises feeling over reason and impulse over tradition. They believe that marriage should be the consequence of love.

In the early 19th century, Jane Austen is defining the wise ideal of modern love. In her novel Pride and Prejudice,  she shows that her idea that to marry only for money is a disaster, but to marry only for love is a terrible folly. In her eyes, marriage requires warmth, tenderness and managerial competence.

From this, Austen concludes that few people are well suited for marriage. In her novels, she portrays marriages that are a little hollow or grim with only a few very happy ones.

In 1859, Charles Darwin publishes The Origin of Species, arguing that humans are descended from the primates and that their drives and basic psychology are inherited and that their ideals are not wholly their own fault.

He argues that we are half apes and for apes to aim for faithful and long egalitarian relationships is to attempt to do something hugely difficult. Darwin implies that humans might by nature be predisposed to, just as many apes are, polygamy, opportunistic sex and leaving one mate for another based on breeding potential.

Free love in the 1960s America argued that society's rules against nudity, same-sex relationships and sex before marriage are forms of sexual repression. Monogamy is being questioned.

Sexually liberated men and women should give up on marriage and jealousy, and adultery and divorce is a romantic idea of what love could be. 

In  2015,  Belgium became the nation with the highest divorce rate in the developed world. 71% of couples will split up because initial expectations were unmet. In the UK, the divorce rate is 42%.

The romantic dream of love is often a disappointment. Intelligent people complain that they can't understand the subject of love.

The future hope for love lies in the idea of sacrifice, that we won't get everything we want from love, relationships or marriage. Our ideals of relationships to unite sex, affection, raising a family, a career, and security will fail by necessity. The idea of sacrifice helps if we consider that getting half of what we want is still a lot compared to what it would be like if we avoided relationships altogether.