This is a great poem right until the end. the use of a statue of Neptune in my opinion is a missed opportunity. the only connection to marriage is that it sounds like nuptials, which it doesn't really. a much better god would have been Vulcan the god of fire but the reason why it is a better god is because he is the son of Juno the goddess of marriage and married to Venus the goddess of love who is meant to have unmatched beauty similar to the last duchess. another reason is that Venus was given to Vulcan similar to how he is asking the count for his daughters hand in marriage but still a good poem so 3 stars