[Agent Richard07]

Sounds like she had some fun times.

She allegedly lost her virginity to a friend's husband. The story goes she was visiting a friend who wasn't home. She was made welcome by the friend's husband and they decided to sleep together. This was before she enrolled in the American Academy of Dramatic Arts in October 1947. She claimed later to have engineered the liaison, not wishing to arrive at college inexperienced in the ways of love. Later when her prospective marriage to Prince Ranier required her to be virgo intacta she was examined by the Royal Monegasque surgeon and allegedly claimed her hymen had been broken while playing hockey at school. - Source

As the truth came out about Grace's sex life as a single girl, in books ever more salacious in their details, it was a shock, sharply at odds with her pristine screen persona.

"She was shy. But physically, she was not shy," the actor Alexandre D’Arcy, who had a monthlong romance with Grace in 1948, told Robert Lacey. "She was … very warm indeed as far as sex was concerned. You would touch her once and she would go through the ceiling." - Source