Books about Love stories (sorted alphabetically)
- Old Gray Homestead Frances Parkinson Keyes
- Old Love Stories Retold Richard Le Gallienne
- Old Man's Love Anthony Trollope
- Old Valentines Munson Aldrich Havens
- Olinda's Adventures: or the Amours of a Young Lady Catharine Trotter
- Only a girl's love Charles Garvice
- On With Torchy Sewell Ford
- Opened Shutters: A Novel Clara Louise Burnham
- Original Belle Edward Payson Roe
- Oswego-joella: "Tienviitan" seikkailuja, intiaanikertomus (Finnish) James Fenimore Cooper
- Other Things Being Equal Emma Wolf
- Our Mr. Wrenn: The Romantic Adventures of a Gentle Man Sinclair Lewis
- Our Mutual Friend Charles Dickens
- Our Mutual Friend Charles Dickens
- Out of the Air Inez Haynes Gillmore
- Over Paradise Ridge Maria Thompson Daviess
- Over the Pass Frederick Palmer
- Ovington's Bank Stanley John Weyman
- Passion for Life Joseph Hocking
- Pathfinder; Or, The Inland Sea James Fenimore Cooper
- path of honor: A tale of the war in the Bocage Burton Egbert Stevenson
- Patricia Brent, Spinster Herbert George Jenkins
- Patsy S. R. Crockett
- Patty Blossom Carolyn Wells
- Paul and Virginia Bernardin de Saint-Pierre