Beware of Pity, by Stefan Zweig

This was a very detailed psychological novel about Lieutenant Hofmiller, a soldier who upsets Edith, a young lame girl by asking her to dance at a ball, as he was unaware of her disability. Unwilling to hurt anyone and wishing to do good, he befriends the family, becomes a regular visitor at their house, and allows them to depend more and more on him until he feels obligated to fulfill their expectations. On the other hand, Edith, used to being the center of attention as the only child of wealthy parents, is unable to accept reality full-time. She swings between elation from living in a fantasy world where her condition is curable and where she can look forward to living life as an able bodied woman, and severe depression when she faces reality and can't accept it. The whole household (and soon, Hofmiller too) has made it their primary concern to keep her as much as possible in her fantasy world. There are two other similar couples in the story with which we can contrast the main couple, both of whom married at least in part due to pity on the part of the husband toward the wife: Edith's parents (her father is a self-made millionaire who made his fortune by taking financial advantage of her mother, whom he then felt obligated to marry) and her doctor and his blind wife. Both made successes of their marriages, as compared to Edith and Hofmiller, whose engagement ends in tragedy on the eve of World War I.