Anyone who thinks otherwise definitely has something undesirable or what they believe is undesirable within their past that they don’t want anyone to figure out because of potential consequences/negative feedback.
Of course all of this isn’t to say that people do not make mistakes, rather, it is to say that secrets should not be tolerated within a relationship.
Those dating or in relationships should be honest with one another no matter how embarrassed, bad, or afraid they may feel about certain pieces of information.