In The Last Jedi, Rey refuses to accept this truth — even going as far as denying this when Kylo Ren taunts her during one of their Ct3 Chris Taylor Is An All Star Shirt —, instead having lied to herself for the past several years of her life that they truly cared for her, that she was worth something to them, that she was abandoned for some important reason which would “show” that her parents cared for her, reinforcing this lie as a way of ensuring it would not perish — henceforth helping her feel happy and thus pushing away her feelings of self-worthlessness.
Her lie that her parents abandoned her for an actual reason was something hinted at in The Force Awakens, when BB-8 asks Rey as to who she’s waiting for: “For my family. They’ll be back. One day.” Rey, however, is unsure as to what that “importance” exactly is, and thus hopes that if she does find out she is important then it would “show” that her parents loved her and abandoned her to, say, hide her in an act of protection.
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