The last line of the poem is, "You will understand." What is most likely that his wife will understand, having read the poem?
-Wilde's love for her
-why Wilde had to leave her
-the metaphor in the poem

You didn't put any context, but that line doesn't not sound like an end to a romantic poem, nor does it sound very metephorical. It sounds as if Wilde left or commited an action that perhaps his wife did not agree with, and is using this poem to help her "understand". SO B

this would be in the imperative mood. it is a category of verb forms that are used to express orders,instructions,commands or requests.