I doubt it's a true story. Such phrases are often used in works of fiction to evoke certain feelings or themes rather than representing actual events. Maybe it takes some inspiration from real life but is not a complete true account.
In 'Black is the Color of My Heart' short story, the color black could be a metaphor for the character's state of mind. It could imply that they are feeling lost or in a state of emotional turmoil. For example, if the story is about a person who has suffered a great loss, the black heart could signify their grief and the darkness that has enveloped their emotions.
Jane was a writer, and black was her favorite color. She wrote all her stories in a black notebook. One day, she was in a coffee shop. She saw a man wearing a black coat. She started to imagine a story about him. In her story, the man in the black coat was a detective. He used his black coat to blend into the night while solving mysteries. Jane's love for black influenced her creativity, and she often used black as a symbol of mystery and intrigue in her stories.