Alain Delon and Monica Vitti in Michelangelo Antonioni's 1962 film "L'eclisse" - great film, and Delon is the most handsome man ever.
Gary Cooper, Miriam Hopkins, Fredric March - Design for Living (Ernst Lubitsch, I don't understand why she couldn't make up her mind about which man she should choose. To me, the obvious choice is Gary Cooper.