With what internal conflict does the speaker struggle in "The Raven"?

The speaker in "The Raven" is agonizing over the death of a beloved maiden named Lenore. He finds it so painful to remember her that he is struggling not to think about her. But he keeps remembering her throughout the poem, and the raven who intrudes into his home and takes up permanent residence only keeps reminding him of his great loss. He transfer his internal struggles to a dialogue with the black bird. But the raven only makes the speaker's suffering worse by giving him nothing but what appear to be nihilistic answers.

In the opening stanza the speaker is trying to forget Lenore by immersing himself in books.

Once upon a midnight dreary, while I pondered, weak and weary,
Over many a quaint and curious volume of forgotten lore,
While I nodded, nearly napping, suddenly there came a tapping,
As of some one gently rapping, rapping at my chamber door. “
“'Tis some visitor,” I muttered, “tapping at my chamber door—
Only this, and nothing more.”

At one point in the poem the speaker asks the bird if there is balm in Gilead. This is the same as asking if there is any hope to be found in traditional religion as promised in various places in the Bible. The speaker is still thinking about the lost Lenore. What troubles him the most about losing her is the thought that she is gone forever--who knows where? This is the thing that troubles most people who have lost a loved one. When King Lear's beloved daughter Cordelia dies, the old man speaks an unusual line which expresses that obvious but somehow unbelievable truth:

Thou'lt come no more,
Never, never, never, never, never.     (5.3)

The raven knows only one word. But that one word seems all too appropriate to the speaker's thoughts and feelings. Therefore the bird itself comes to symbolize the speaker's sense of hopelessness. The bird refuses to leave. By perching on the bust of the goddess of wisdom, Pallas Athene, the bird further represents the cold, hard truth that Lenore is dead and it is useless to imagine any way in which the speaker could ever be reunited with her. In the end the speaker is totally defeated in his internal struggle to "find surcease of sorrow, sorrow for the lost Lenore." He gives in to eternal grief. Nothing can relieve his anguish but his own death.

And the Raven, never flitting, still is sitting, still is sitting
On the pallid bust of Pallas just above my chamber door;
And his eyes have all the seeming of a demon's that is dreaming,
And the lamplight o'er him streaming throws his shadow on the floor;
And my soul from out that shadow that lies floating on the floor
Shall be lifted—nevermore!

Edgar Allan Poe's wife Virginia, whom he married when she was only thirteen, was still alive in 1845 when he published "The Raven," but she was in poor health and died of tuberculosis in January of 1847. It seems likely that he was expressing his feelings about his pending loss of Virginia in "The Raven."