Prince Harry and Meghan Markle are expected to attend the Coronation this spring.
A royal author, Tom Bower, claims their attendance will "ruin it" for King Charles III.
Bower thinks people are sick of the Duke and Duchess of Sussex.
He called King Charles a "weak" man for worrying about his youngest son.
Bower suggests the couple should completely scrap any idea of coming to the UK in May.
Bower believes Harry's presence at the Coronation will overshadow the event.
He thinks Charles needs to make a decision now regarding Harry's attendance.
The Coronation is scheduled to take place on May 6 at Westminster Abbey.
Bower claims people are getting "sick to death of Harry."