Forget about him. He cheated on you, which means he's not worth it to begin with.
Well, you need to give us the choices before we can give an exact answer but normally you can evaluate the tone by thinking about the context and meaning.
some examples of strong disapproval might be: "She's such a horrible person" or "I really hate this lamp it's ugly" The bolded words show the strong disapproval.
But most likely you should be able to find it by evaluating tone.
Taking into account the statement above: "For several days ensuing, her name was unmentioned by either Usher or myself: and during this period I was busied in earnest endeavours to alleviate the melancholy of my friend.What does this excerpt reveal about the narrator of the story?"
The answer is: it describes what the narrator experiences in the story.
Hope this helps.
Is there a question for this