GRACE KELLY - GRACE KELLY: AN UNFULFILLED LIFE?

Hollywood legend GRACE KELLY always regretted her decision to marry PRINCE RAINIER of Monaco - according to a new book.

Scribe J. RANDY TARABORRELLI claims the REAR WINDOW star had a miserable marriage and wished she hadn't turned her back on her glittering acting career.

Quotes in the book include Grace saying, "Do you realize if my mother hadn't been so difficult about OLEG CASSINI (a designer), I probably would have married him?

"How many wonderful roles I might have played by now? How might my life had turned out? That one decision changed my entire future."

In the book ONCE UPON A TIME: BEHIND THE FAIRYTALE OF PRINCESS GRACE AND PRINCE RAINIER, Taraborrelli also claims her decision to marry was partly to impress her distant, unloving father JACK KELLY.

The book also reveals HIGH SOCIETY star Kelly's attempt to get back into acting in ALFRED HITCHCOCK's MARNIE was so controversial in Monaco, she had to back out.