Irene Dunne was Cary Grant's favorite leading lady. He never publicized it - he didn't want any of the other actresses he worked with to feel inadequate (even though the notion that some of those women would feel inadequate is ridiculous) - but it was true. Irene Dunne was his favorite - he liked the way she smelled.
Cary Grant did not deal with "floozies", he never had good chemistry with those girls. He needed a Woman, a real Woman. Intelligent, savvy, sharp witted, and not afraid to cross swords with him. Irene Dunne was one of these women - one of the best. They were perfect sparring partners, and their ability to trade the upper hand mid-conversation only made their relationship more real and comedic.
I love this picture because he looks mad, really mad. If he'd been giving this look to anyone else, frankly I'd be a little concerned. But then I see her face, and I can just tell that he won't be able to stay mad for long.
I love her face here. It's at the end of The Awful Truth, when Cary Grant isn't sure what to do. They're minutes away from being "officially" divorced, and he's finally realized that he's still in love with her. They've both been up all night (in adjoining rooms at her parents' cabin) and the wind keeps blowing the door connecting them wide open. He goes into her room and starts messing with door, trying to figure out how to keep it shut... but he can't keep it shut unless he's on her side of the door, so he sort of scratches his head and looks over at her. She then pointedly glances to the corner of the room (where there is a chair that can easily be wedged under the doorknob, hence locking them in together...) and sort of gives him this face, like "uh, are you seriously still standing over there thinking about this??"