Insecurity comes when you pose a question about your worth and hope that someone will provide the external validation to prove or show you that you are worthy, lovable, attractive, cool, etc. Our parents are supposed to be our mirrors and need to provide a positive source of validation when we’re children. If they did not do that for us, or projected their pain instead of reflecting our beauty, you seek other mirrors in relationships to provide that validation as a confirmation of what you think is true about yourself.