What is the poem "A Dream" by Edgar Allan Poe about?

Although in other poems he says that he has dreams of loss when he's asleep, in this poem in his waking life, which is also a dream (the same dream that he dreams at night but now has awaken in and it appears real), also has loss and makes him broken hearted. But this dream the world calls "reality" where everyone is arguing and where the speaker has lost someone he loves, he can use this past to cover the reality of the present and make him happy