Anthony Lane has a masterful article on Grace Kelly in The New Yorker.

Two passages of especial note:

“High Society,” which was filmed during Kelly’s engagement, is a tarter response than its reputation might suggest, with Kelly, playing the ex-wife of Bing Crosby, veering back toward him on the eve of her second marriage. (And enjoying a bracing dip with Frank Sinatra along the way.) It is customary to denigrate “High Society” by comparing it with its parent, “The Philadelphia Story,” but I knew the child first, when I was a child, too, and nothing can undo the movies that we are led to in our youth, or the skein of impressions that they leave. I remember my mother explaining to me, drawing on who knows what store of apocrypha, that Prince Rainier had watched the scene of his wife-to-be, droopy with drink, being lugged through the moonlight in Sinatra’s arms, both of them in towelling robes, and that His Serene Highness had bridled at the outrage and declared that her works be outlawed, henceforth and on pain of death, within the bounds of his kingdom. This struck me as precisely how a jealous monarch should behave, and the twin sense of Kelly as both sovereign and subversive was planted in my brain.

…

The sex life of Grace Kelly, like the home life of the Incas, is one of those distant but down-to-earth matters which we can investigate in depth, and muse upon at length, but never really hope to understand. According to some observers, she herself may not have grasped its implications; in the words of a columnist at Photoplay, “I wonder if Grace Kelly knew she had so much S.A.” To which the only proper response is, W.T.F.?