By marrying Prince Harry, Meghan is technically a Princess by marriage and is therefore entitled to the style.
But because she was not born into the Royal Family, like for example Princess Charlotte and Princess Beatrice were, she cannot technically be called Princess Meghan.
This is also the case for Kate, Duchess of Cambridge, who received the style of Princess William of Wales when she married Prince William in 2011.
Nowadays members of the Royal Family do not tend to publicly use their husband’s name in this way.
