The only one of Louis XV’s daughters to marry was the eldest –Elisabeth. She married her second cousin, one of the younger sons of the King of Spain. They became the Duke and Duchess of Parma.
Twelve years after Elisabeth left Versailles, her twin sister Henriette died, leaving Adelaide, the eldest of the four surviving daughters at court.
There was never any serious question of marriage. There were no available Catholic princes the right age and Adelaide had no interest in marrying beneath her station as her eldest sister believed she had.
With the arrival of her father’s latest (and final) mistress Madame du Barry, Adelaide moved from the apartment she had occupied on the first floor and took over Madame de Pompadour’s former apartment on the ground floor. She stayed there for the next twenty years until the French Revolution.