Explanation:

Me only cruel immortality

Consumes; I wither slowly in thine arms,

Here at the quiet limit of the world.

Answer: It is one of the most conspicuous and noteworthy statements which have occurred in the famous poem, “Tithonus” composed by Lord Alfred Tennyson. Here the poet describes the misery of old Tithonus. 

Tithonus is a very handsome and agile young man. The goddess of dawn, Aurora falls in love with him. She takes him to Zeus and begs for immortality for him. What she forgets to want is the everlasting youth for Tithonus. However, Zeus grants her prayer. Aurora keeps him with her. But with the passage of time, Tithonus grows old. Whereas he does not die like the average people on earth. Now he is miserable. He has lost his physical strength and passion. His blood does not glow at the sight of his dark eyes of Aurora. But Aurora is evergreen. She does not lose her beauty, charm, and youth. So she can live with old Tithonus no longer now. Hence Tithonus cries for a release from his accursed immortality. He keeps on a withering day after day. In the very morning, his beloved rises newly. She peeps in the horizon like an unravished bride. But Tithonus fails to cheer her up. He only feels depressed with a deep sigh looking at her. He is becoming thin in her beautiful hands.

In fact, we find an elegiac tone here. The sudden death of Hallanm shocks Tennyson most. This deep shock provides him with an elegiac tone which has been expressed in these lines.