On Valentine's Day, there's the temptation to believe that somewhere out there is "The One": a soulmate, a perfect match, the person you were meant to be with.
Across history, humans have always been drawn to the idea that love isn't random. In ancient Greece, Plato imagined that we were once whole beings with four arms, four legs and two faces, so radiant that Zeus split us in two; ever since, each half has roamed the earth searching for its missing other, a myth that gives the modern soulmate its poetic pedigree and the promise that somewhere, someone will finally make us feel complete.
In the Middle Ages, troubadours and Arthurian tales recast that longing as "courtly love", a fierce, often forbidden devotion like Lancelot's for Guinevere, in which a knight proved his worth through self-sacrifice for a beloved he might never openly declare.
By the Renaissance, writers such as Shakespeare were talking of "star-crossed lovers", couples bound together by an overwhelming connection yet pulled apart by family, fortune or fate, as if the universe itself both wrote their love story and barred them from a happy ending.
In more recent times, Hollywood and romance novels have sold us fairy tale love stories.
But what does the latest science say about soulmates? Is there a particular special someone out there for us?
My ex and I have almost nothing in common but kink. But even 10 years after the divorce, we fall back into old routines when we meet up.