NOTE: this is a subjective question. Therefore, I will provide my own opinion. Feel free to change anything in this answer.
Answer and Explanation:
"Was It a Dream" is a short story by Guy de Maupassant. The main character and narrator spends most of the story telling readers about his suffering after losing the woman he loved. He doesn't seem able to get over her death. Everything reminds him of her and, now that she is buried, imagining her body, her beauty, decaying is torment to him. She died after walking in the rain. Caught a cold - which was probably not a mere cold, but that's what the story says - and never recovered.
The narrator decides to spend a whole night at the cemetery, weeping next to her tomb. However, when the night comes, to his surprise, all the tombs are opened by the very skeletons and corpses inside them. They erase the beautiful sayings their relatives had engraved on their tombs and write the truth about themselves. All of them had committed sins, and the narrator's beloved one was not an exception. She reveals that she walked out in the rain to deceive (cheat on) him.
I believe it is better for the narrator to know the truth about her. His heart was already broken for having lost her. Now that he knows she was unfaithful, his suffering over her death may finally cease. He may very well realize that she is not worth the pain, and that he should carry on with his life. Now, the narrator can quit idolizing someone who is undeserving of his affection.