Historic power of the Monarchy Henry the VIII wants to marry someone he marries them and damn what anyone thinks .
Modern power of the monarchy:-
“In 1930, the Prince, who had already had a number of affairs, had met and fallen in love with a married American woman, Mrs Wallis Simpson. Concern about Edward’s private life grew in the Cabinet, opposition parties and the Dominions, when Mrs Simpson obtained a divorce in 1936 and it was clear that Edward was determined to marry her.
Eventually Edward realised he had to choose between the Crown and Mrs Simpson who, as a twice-divorced woman, would not have been acceptable as Queen.”
King has to Abdicate.
Our modern constitution is built around the Monarchy but it clearly does not have the Monarchy at the heart of power.