Meaning: A guy recently broke up with a possibly long-term girlfriend and still thinks about her. Since his friends are urging him to move on, he finds another girl and tries to replace his ex with her. But then he realizes that they are not the same person at all, no matter how much he wants to "believe the lie", he can't. So he explains to his ex through this song in hopes of getting her back. He knows what he's gotta do now. It doesn't matter how beautiful she is, "she's not you".