Based on the story's outcome and this passage, why is the statement I wouldn't give her up for nothing on earth" ironic?

What is the effect of narrator's word choice on the tone of this passage? the words "my heart shrank within itself" create a fearful tone. the words "better-omened" set a hopeful tone. the words "wounded his fellow" develop a remorseful tone. the words "struck harsh upon my ears" suggest an irritated tone.