The relationship between the old man and the fish is one of respect and dignity. The old man reveres the fish constantly talking to him and asking what he's got next for him. He is awed by his size and by the fact that he keeps going and trying to escape. That's why he's so upset once the battle is finally over. He knows he's beaten this fish and he would like to bring him in with dignity and respect. When the sharks start to get after him, he knows that he's done a disservice to the fish by not being able to get him in and save his body from the sharks. You can also support this idea by talking about the point when the fish launches and the old man mentions that their eyes meet. The fish is impressed with the old man's ability to hang on, something others have not been able to do, as evidenced by the number of hooks hanging from the side of his mouth when the battle is finally over.
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