In Graham Greene's The Heart of the Matter, the protagonist Major Scobie's major weakness concerns his excessive feeling of pity for individuals, such as his wife. It cannot truly be said he still loves his wife, yet his feelings of pity for her help keep the marriage together, as we see him explain early on:
These were the times of ugliness when he loved her, when pity and responsibility reached the intensity of a passion. (p. 22)
It's this feeling of pity that also creates problems for him as a character, especially since his pity also drives his sense of duty. For example, pity drives his sense of duty to provide his wife with financial means to take a trip to South Africa. He feels so driven by duty that he borrows money from Yusuf, a very dangerous Syrian smuggler who soon finds a means of blackmailing Scobie, one event that leads to Scobie's final demise.
However, his sense of duty can also be seen as a strength even if it leads to his suicide by the end of the novel. Out of duty, he does everything he can to prevent his wife from learning about his affair with widowed Helen, whom he also pitied. He even fakes being purged of his sin by taking Holy Communion just to keep up appearances, an action he knows may lead to eternal damnation. Yet, out of a sense of duty, he is willing to sacrifice his own soul to damnation for the sake of protecting his wife from being hurt by knowledge of the affair.