The Wings of The Dove by Henry James.
 
Milly Theale, a wealthy American heiress, falls ill while traveling in Europe. She meets Merton Densher, a young Englishman, and they fall in love. However, Merton is already engaged to Kate Croy, a woman with designs on Milly's fortune. Kate and her aunt, Maud Lowder, manipulate Milly into believing that Merton loves her. Milly, unaware of the deception, sacrifices her own happiness to secure Merton's future.