The strikingly beautiful Capucine may not be much of an actress, but she's not helped much by a script which calls for her to behave like a non-stop pill from the minute she's introduced. Male screenwriters unfamiliar with how women actually think are often guilty of writing about "beauty" as though it were an actual character trait rather than a physical attribute.
In the case of Hallie Gerard, so little of the character's much-talked-about passion, restlessness, or joy is conveyed that we're left to imagine she's fought over by Dove and Jo simply because she's so outrageously pretty. If the Hallie we now see is supposed to represent a broken woman whose life-force has been drained out of her by her having "fallen down the well," all the backstory we're left to imagine requires an actress substantially more skilled than what we're given. You get about as much emotionally out of Capucine as a walking/ talking entity as from one of her model photo shoots from the '50s.