Because Prince Harry needs the Queen's permission to get married
In order to marry his fiancée Meghan Markle, Prince Harry must seek permission from Queen Elizabeth. The tabloids do not say this, assuming some sort of royal etiquette, but English law establishes it.
That things between William's little brother and the actress are going well is pretty clear. The two continue to keep a low profile, but have been seen several times together and Meghan has met part of the family, first Carlo and William, then Kate.
Now only you are missing, Her Majesty.
Grandmother, but also the most famous and long-lived sovereign in the world.
The fate of the relationship with Harry and - who knows - a future marriage will depend on his judgment. Here because:
The law
In 1772, King George III passed the Royale Marriages Act, a provision that stipulated that direct descendants of the monarch must have the king's approval in order to marry.
Once the union was approved, the marriage or engagement could be considered valid.
The law was enacted in response to the choice of King George's brother Prince Henry to marry Anne Horton, a widowed commoner the year before, without her consent.
The changes
The act has been modified over the centuries, smoothing out the most rigid parts.
In 2011 the Perth Agreement proposed by David Cameron limited the requirement to apply for permission only to the first six descendants in the line of succession to the throne.
This, however, means that Harry is still among the heirs who must submit to the Queen's judgment, being fifth in the line of succession, after Charles, William, George and Charlotte.
Until now, however, Elizabeth II has never denied her consent.
The timing
The relationship between Meghan and Harry is going very well, so much so that the actress has already met a large part of the family.
The first was Prince Charles, then it was William's turn and recently Kate and Charlotte too (George was in kindergarten).
However, it may still take some time before the scion of the Windsor house decides to bring his fiancée in the presence of Her Majesty.
Kate, for example, had to wait four years before being introduced to Elizabeth II at the wedding of William's uncle, Peter Phillips, in 2008.
Prior to the royal wedding between the Duke and Duchess of Cambridge, the Queen signed a formal approval note allowing the wedding.
The disputes
Unlike Harry, Meghan Markle has already been married once to producer Trevor Engelson, from 2011 to 2013.
This still makes some conservatives turn up their noses today.
Historically, in fact, the hypothesis that a member of the royal family could marry a divorced person is frowned upon.
Princess Margaret, for example, was forced to end her relationship with Colonel Peter Townsend because he was divorced and she had to respect the indissolubility of Christian marriage. In 1936 Edward VIII abdicated in order to marry his beloved - and divorced - Wallis Simpson.
The precedent
Either way, Harry shouldn't have any problems, at least not from that point of view. Times have evolved, as has the thinking of the monarchy.
Elizabeth II proved to be in step with the times already a few years ago, when in 2005 she allowed her son Charles to finally marry Camilla Parker Bowles. And in that case it was the direct descendant to the crown.
Harry and Meghan more and more united
A few days ago Harry and Meghan were paparazzi hand in hand as they left a London club.
According to the well-informed, the two would take advantage of every free moment to see each other.
The Prince went to visit her overseas after returning from an official trip to South Africa, while the actress now seems at home in London, where she flies between a break and another on the set.
The two have also already made the first tests of coexistence, at least for the few days they spend together. And in the UK, bookmakers are even betting on hypothetical weddings within the year.