How is the concept of human relationships explored in the poem "Lullaby" by W.H. Auden?

"Lullaby" is an interesting poem in its sheer universality; it represents a relationship most of us recognize, while at the same time rejecting the traditional trappings of love poetry in its acknowledgement that neither the speaker nor his beloved are perfect. The universal sentiments Auden expresses are even more significant because Auden himself was a gay man whose love poetry was to and about other men, yet the point this poem makes is that all human relationships are, at their core, about the same things.
The speaker describes himself as "faithless" while his lover is "mortal, guilty," and yet, in the eyes of the speaker, "entirely beautiful." He knows that this is not reality, but to him it is immaterial. The second stanza incorporates "supernatural" elements and philosophical questions of "soul and body," describing the way "universal hope and love" make knowledge of a beloved's faults drop away. This poem, in particular, focuses on an island in time, "this night," when the lovers need not think of "the cost" of their faults or infidelities; rather, they must treasure each "whisper," "thought," "kiss" and "look," as being the more important truths.
"Beauty, midnight, vision dies," begins the final stanza of the poem: all ephemeral things eventually come to an end, including the beauty of the beloved, the fleeting moment in time described by this poem, and the vision of the lover. Ultimately, however, this is not important, because the nature of human relationships is that "every human love" will forgive faults and guilt in the lover, knowing that this is simply how people are.