Don Juan DeMarco is a 1994 American romantic comedy-drama film starring Johnny Depp as John Arnold DeMarco, a man who believes himself to be Don Juan, the greatest lover in the world. Clad in a cape and domino mask, DeMarco undergoes psychiatric treatment with Marlon Brando's character, Dr. Jack Mickler, to cure him of his apparent delusion. But the psychiatric sessions have an unexpected effect on the psychiatric staff, some of whom find themselves inspired by DeMarco's delusion; the most profoundly affected is Dr. Mickler himself, who rekindles the romance in his complacent marriage. Wikipedia
Don Juan: You know, my friend, until this afternoon, I had always believed that a man could love only one woman. I have been badly misled. It is absolutely incredible to me that just a few hours ago, Dona Julia was the only woman who existed, and now, now, there is the magnificent Sultana Gulbeyaz.