Mr. Imperium by Don Hartman

Frederica Brown, played by blonde bombshell Lana Turner, is vacationing at an Italian resort when she not-so-accidentally stumbles into a man who calls himself Mr. Imperium. The two strike up a romance that’s put on pause when Mr. Imperium confesses that he’s a — wait for it — European crown prince. Oh, and his father is gravely ill, and he must leave at once. Years pass, and while the prince tends to his father, Frederica becomes a movie star. He travels to California to rekindle their romance — only for his duties to get in the way once more.