Why is each of his novels so different?

Though every novel is a love story set in Eastern North Carolina, each novel has a different theme, and the theme not only sets the tone for the novel, but influences everything within the novel: characters, voice, writing style, and settings. The themes for each novel, in order of publication, were: (1) The Notebook -- unconditional, everlasting love, (2) Message in a Bottle -- love after grief, (3) A Walk to Remember -- the beauty, power and innocence of first love, (4) The Rescue -- love as savior (or rescue), (5) A Bend in the Road -- love and forgiveness, (6) Nights in Rodanthe -- love and sacrifice, (7) The Guardian -- love and danger, (8) The Wedding -- love and renewal.

Because the themes were different, the narrative voices, characters, writing style, and length all varied dramatically, and the settings were chosen for maximum effect within the story.