At the end of Guess Who's Coming to Dinner (1967), everyone is gathered to hear if Spencer Tracy will give his blessing to his white daughter marrying a black man. It was Tracy's last film; everyone involved knew he was dying. Production was arranged so that he would need to work only three hours a day. In his speech, giving his consent, he compares what the young couple feel for one another to what he has felt for his wife, played by Katharine Hepburn.
Tracy and Hepburn had been a (discreet) couple since 1941. This was their ninth film together. As Tracy's character begins to make the comparison to what he has felt for his wife (at about the 35 second mark in the clip below), he moves across the room so that Hepburn is in very soft focus on the right side of the shot. Whatever Tracy was thinking as he spoke, watch Hepburn's face (her eyes glisten, her lip quivers), and you have to think that she is relating his words to their real lives, hearing them when she knows she will soon lose him.
Tracy died 17 days after filming was completed. Hepburn claimed she could never watch the finished film.