How would you analyze the poem "Song" by Alun Lewis?

The poem “Song” was written by the Welsh poet Alum Lewis, who died in India during World War II.
The themes addressed in the seven stanza poem are love, loss, and ultimately, the acceptance of loss. The tone is melancholy and forlorn.
In the poem, which is spoken from the wife’s point of view, a young soldier leaves his wife to join the fight. His leaving makes her miserable enough to feel ill.  It is their hope that she is pregnant. Unfortunately, both are disappointed when she is not.

And where he's left his promise
Life did not turn or kick
The seed, the seed of love was sick.

In her grief, she misses him dearly, but the months of his absence pass until he dies in a shipwreck and is lost at sea. She explains that they never planned for life as it occurred but slowly, she learns to live without him and to accept her loss. The process of acceptance is slow and difficult but ultimately, it does happen.  
Each of the seven stanzas follows an ABCBB rhyming pattern, and contains vivid imagery and similes.

And my bed was like a grave
And his ghost was lying there.

The first stanza describes how the wife felt when her love left, and she discovered she was not carrying his child. The second stanza describes her grief and loneliness; while the third brings her to the realization his ship is lost at sea. In the fourth stanza, which corresponds with the fourth month of his absence, she imagines him to command her not to think of him in his permanent absence. In the fifth stanza, Lewis describes, with vivid sea life imagery, the soldier’s watery grave. Stanza six finds the wife lamenting life’s twists and turns, and it describes how the coral reef continues to grow while her husband lays dead in its midst. This is a metaphor for how life progresses even in the face of a loved one's death.  Finally, in the seventh stanza, as time passes, she, with great difficulty, comes to accept his loss.  

The turning seasons wither in my head;
All this slowness, all this hardness,
The nearness that is waiting in my bed,
The gradual self-effacement of the dead.