The royal biographer added that Harry's situation to that of his royal relative Edward VIII who infamously abdicated in order to marry his American divorcee bride, Wallis Simpson.
"I make frequent comparisons between the current situation and Edward VIII’s abdication crisis, both are essentially conflicts between love and duty," he explained.
"Harry stands for love and Harry has gone into exile."
Speaking of Harry and Meghan's former close bond with Prince William and Duchess Catherine Middleton, Lacey added: "They were called the Fab Four, the same name that was given to the Beatles. But just as Yoko Ono stole John Lennon, so Meghan has stolen Harry."
The report is yet another blow for the Sussexes who were slammed by royal biographer Angela Levin for their $200 million deal with Netflix.
Speaking to Good Morning Britian, Angela said Harry has made a "terrible error" with his decision, explaining it would be unrealistic to assume the streaming giant won't expect the couple to spill juicy regal secrets.
"I think [Harry and Meghan] are being naive as they have been about lots of things in that they don’t realise that a big company like Netflix is going to want its pint of blood," she said.
"They’re going to delve in and get a lot of information that will absolutely decry the Royal Family.”
There were even talks that a "full-out war" with the Queen could arise if Harry and Meghan spill any more details of their life at the palace.
"I think Harry would be foolhardy at this point to have a tell-all,” royal expert Marlene Koenig warned, before alleging the couple are in enough “hot water” over the Finding Freedom book.
"I think they would be foolhardy, absolutely crazy because it would not help their situation and it would certainly not help their situation with the British tabloids.
"I think a full-out war would be declared on them and I don't think that should happen but that's the last thing they should be doing,” she added.