Hello Aspirant,

First of all we have to understand about why Dover beach is considered as a Dramatic Monologue, because it is the poem based on drama in which there are two people, where one is addressing other but second speaks nothing. If second also speaks than poem would be converted to a dialogue.

In this poem Arnold is the speaker and his bride is a listener, they both were spending some time together in 1851.

This poem represents the theme of relationship, loss of faith, human suffering and likewise.

I hope this information helps you.

Good Luck!!