Because

Girl meets boy, they fall in love. A typical story with an unusual twist. The boy, Credence Barebone, is an abused orphan. Lucy is an Irish girl with a dirty past. Another thing about her, she's from the future. The not-too-distant future of 1970. A bright, hippie baby in a, dark, sad 1926.
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Each chapter has a Beatles song to go along with it, a video with the song will be in the media of each chapter. Feel free to skip over the lyrics in dialogue form, I'll put "~~" before them so you know when it's coming. But the song does, sometimes, hold meaning to the story.