This novel is based on the nineteenth-century romantic or gothic novel, a literary genre which can trace its origins back to the eighteenth century. Although Fowles perfectly reproduces typical characters, situations, and even dialogue, the reader should always be aware of the irony inherent in Fowles' perception; for his perspective, however cleverly disguised, is that of the twentieth century. We see this both in the authorial intrusions, which comment on the mores of people in Victorian England, and in his choice of opening quotations, which are drawn from the writings of people whose observations belie the assumptions that most Victorians held about their world.
Fowles is concerned in this novel with the effects of society on the individual's awareness of himself or herself and how that awareness dominates and distorts his or her entire life, including relationships with other people. All the main characters in this novel are molded by what they believe to be true about themselves and others. In this case, their lives are governed by what the Victorian Age thought was true about the nature of men and women and their relationships to each other. The French Lieutenant's Woman of the title, for example, is the dark, mysterious woman of the typical Victorian romantic novel.
Sometimes the villainess, sometimes the heroine, such a woman was a symbol of what was forbidden. It is this aura of strangeness about Sarah Woodruff that first attracts Charles Smithson's attention. The story that develops around this pair echoes other romantic novels of a similar type, wherein a man falls in love with a strange and sometimes evil woman.
Charles' relationship with Ernestina Freeman creates another sort of romantic story, one that formed the basis of many Victorian novels. In the present story, the romantic situation which develops around the pair of aristocratic young people is not allowed to prevail over the forces, including the dark lady, that would normally keep Charles and Ernestina apart. Thus Fowles uses the popularity of the comedy of manners and combines it with the drama and sensationalism of the gothic novel and, using several stylistic conventions, creates a masterful, many-layered mystery that is one of the finest pieces of modern literature.