I saw this movie some years ago. It was a black and white romantic com. It may have starred Cary Grant or someone like that. There was some arguing between the guy and the gal who were in a hotel with a door between adjoining rooms. Right at the end there's a 2 second shot where the cat (which has a minor part in the movie) is seen on its hind legs pushing the door between the rooms closed to prevent the couple arguing.