Of course,

"Why did you not make the bed?"

Grace Kelly was one of the finest creatures to ever walk this globe, and a v decent actress, too.  But it is plain to see that Ingrid Bergman was Hitch's v favorite blonde.  Although all votes will be counted for Eva Marie Saint and Madeleine Carroll, as well.

The proof for my thesis is Rear Window, a film Grace Kelly starred in.  The film is based upon the life stories of photographer, Robert Capa, and the actress/"model" he had an affair with, Ms Bergman.  Hitch could not use Ms Bergman at the time, as she was currently "blacklisted", due to her affair and subsequent marriage to Roberto Rossellini.

(Plus, who knows if Ingrid would have done the film anyway, due to the extreme closeness of the subject matter.  She was prob v comfortable, letting another actress play the role since she was not a jealous soul.)