Hey there!
(Again, not entirely sure...) I think the symbolism is when he says "Yes! - that was the reason" because a lot of people probably think this is a little bizarre, that the angels killed his Annabel Lee, so he is saying "Yes! - that was the reason" and it makes him sound like he is a little off in the head, that his mental state may not be great, because he is obsessing over the angels being jealous of their happiness. SO, you could put, "The symbolism is "Yes! - that was the reason" because it shows that his mental state may not be great because he is obsessing over why Annabel Lee died; according to Poe, it's because the angels were jealous."
Have a terrificly amazing day!
