The style of writing in Pale Horse, Pale Rider is melodramatic. This tone fits the subject of the story, which is the doomed love of Miranda and Adam as it is lived out against a panorama of war and pandemic.
The melodramatic language reflects the heightened intensity of the times, when death seems to hang over everybody's head. The words reflect, too, Miranda's state of mind, which is literally fevered because she is coming down with the influenza that was killing people in droves in 1918. She is also metaphorically fevered, filled with anxiety about Adam, her beloved, going off to World War I.
Miranda's fevered vision of Adam as she collapses under the strain of influenza is laced with melodrama. She sees Adam in
an angry dangerous wood full of inhuman concealed voices singing sharply like the whine of arrows and she saw Adam transfixed by a flight of these singing arrows that struck him in the heart and cut shrilly cutting their path through the leaves.
This long clause has a breathless, emotive quality due to the "ands" and the lack of commas. The feelings conveyed are heightened by dramatic words like "angry," sharply," and "shrilly," and phases such as "struck him in the heart." This is not casual or conversational prose.
The language at the end also reflects Miranda's heightened emotions as she deals with the irony that Adam died, not in the war but from contracting influenza. She sees him as a ghost beside her:
She ... clung to the lie, the unpardonable lie of her bitter desire. She said, "I love you," and stood up trembling.
Adjectives like "unpardonable" and "bitter" increase the emotional effect of the already powerful nouns "lie" and "desire." The standing up "trembling" conveys dramatic intensity. This is the language of melodrama, unabashedly playing on the emotions.