It’s a drag rolling over in bed to find nothing instead of something. Real happy with the imagery and wordplays here.

[When my love beside I cannot shake,
Horizontal’s the lie I fabricate.]

Each morning as you depart,
        Our sleepy feather bed,
        A slight depression always sets,
In the down,
And in my head.
So into your body,
My pillows I reshape,
To cushion the sorrow,
To fill the hollow,
Your absence doth embed.