What is the theme in The Well of Loneliness by Radclyffe Hall?

This novel centers on a woman born in the late part of the nineteenth century who discovers early in her life that she is not like most girls her age. Stephen dislikes dresses and dolls, preferring to wear trousers and hunt alongside her father. Stephen dresses up like Nelson as a small child, pretending to be the great hero as she races around her father's property. Later, Stephen prefers to learn fencing than the social etiquette most other girls spend their days learning. Stephen knows she is odd, knows that she does not fit in with her contemporaries. Even her own mother, Lady Anna, rejects her daughter out of an instinctive understanding that there is something different about her.