What is the theme in All About Love by Stephanie Laurens?

As the title says, this is a novel about love. Phyllida is a very intelligent woman who understands a lot that others don't. But she does not understand what love is. Growing up without a mother, there was no example of romantic love in her home. The couples in town are not very good examples of love. They are uncaring and unfaithful. Phyllida is not sure what love is, but she wants to learn. It is the love of Mary Anne and Robert that inadvertently leads Phyllida to be in Horatio's house during the murder. As she is searching for another's love letters, she finds Lucifer and eventually love.