The title, "Correspondence," and the line beneath it, "a letter from the war," tell us we're reading a message sent from far away. The two short lines that follow seem to be what the writer says. Someone at the front, or touched by the war, is trying to stay close to a partner at home.
The image is odd and striking: "I try being the ice / in our bed." Ice is cold, and a bed should be warm. So the speaker is imagining themselves as the chill that fills the empty space where they should be. The word "try" matters. It suggests effort and failure, as if the speaker can't be there as a body, only as an absence that the other person feels.
The mood is lonely and quiet. There is longing here, but also a hard honesty: the speaker doesn't promise comfort, only a cold kind of presence. The brevity makes the silence around the words feel large.