What are the motifs in On Golden Pond by Ernest Thompson?

One of the strongest but subtlest motifs of this play is love and marriage. This play is based on two people, Ethel and Norman Thayer, who have been married so long that they cannot remember a time when the other was not around. The length of their marriage is not discussed throughout the play, it is simply stated as fact. However, as the play progresses, the importance of this marriage becomes more and more evident to the reader. Norman relies on Ethel not only to care for him but for her companionship and protection.