I don't consider this a young adult book. It is a historical romance.
The Precarious Game of Love. Abbie knew that one day she would marry Douglas -- that is, until Lorena arrived on the scene. Lorena had a fliratious mix of charm and recklessness that was hard for any man to resist, and Douglas was no exception. What troubled Abbie, too, was that Lorena, an impassioned Southerner, was using her wiles to sway Douglas toward the rebel side in the War Between the States. Nothing was turning out as Abbie had dreamed it -- nothing in her past had prepared her for Douglas's uncertain heart, for his uncertain loyalties, for this precarious game of love. Set against the sweeping background of the Civil war, Phyllis Whitney spins a dramatic tale of love and conflict.
A Romance: Against the sweeping background of the Civil War, Phyllis Whitney spins a dramatic tale of love and conflict. (paperback)