Ethan Frome is set in Starkfield, a small village in the Berkshires. The village's name fittingly reflects the novella's bleak and desolate atmosphere. The three central characters are constrained by poverty, Puritanism, and the harsh realities of rural New England life. In Ethan Frome, it always seems to be winter.

Passion and repression are central themes in Ethan Frome. The three main characters are deeply passionate, yet their unspoken emotions starkly contrast with their austere surroundings and stern manners. In such an environment, even the simplest comment is laden with meaning and emotion.

Another significant theme is the youthful desire for freedom versus the adult acceptance of responsibility. As a young man, Ethan Frome hoped to escape the burdens of a family property that barely supported him and his wife. However, by twenty-eight, he is burdened with a hypochondriac wife, a mortgage, and an unprofitable business. When he dreams of running away with Mattie Silver, he realizes he doesn't even have enough money for two train tickets. Furthermore, he can't leave his ailing wife with an estate that cannot sustain her. Like many of Wharton's characters, Ethan feels trapped in a situation with no apparent escape.

Frustration
Frustration is a central theme in Ethan Frome. At times, this frustration arises from an oppressive environment, while other times it originates from the characters' personalities. Ethan's initial aspirations to become an engineer are thwarted by the necessity to care for his ailing parents and the family farm. He had always dreamed of "living in towns, where there were lectures and big libraries and 'fellows doing things.'" His marriage to Zeena exemplifies frustration, not only due to her hypochondria and their childlessness but also because of their differing interests. "Other possibilities had been in him, possibilities sacrificed, one by one, to Zeena's narrow-mindedness and ignorance. And what good had come of it?"

Mattie is similarly constrained by her poverty and lack of skills. Even Zeena experiences frustration. As the narrator explains, "She had let her husband see from the first that life on an isolated farm was not what she had expected when she married." Although Zeena despises Starkfield, she could never have adapted to a new town that looked down on her, leading to the couple never relocating. The theme of frustration is further emphasized by the characters' inability to articulate their feelings in Ethan Frome. None of them are adept at expressing themselves. Wharton even referred to the characters in the novel as her "granite outcroppings." While walking Mattie back to the farm, Ethan, deliriously happy in her presence, struggles to find a "dazzling phrase" to impress her but manages only to grumble, "Come along." Frustration is also evident in Ethan and Mattie's yearning for each other. Their physical contact, though passionate, is mostly limited to secretive handholding. When Ethan witnesses Ned Hale and Ruth Varmus kissing under the Varnum spruces, he feels "a pang at the thought that these two need not hide their happiness."

Individual Responsibility
Closely tied to the theme of frustration is the notion of individual responsibility, particularly Ethan's sense of duty that binds him to his circumstances. Critic Blake Nevius identified the "great question posed by Ethan Frome" as "What is the extent of one's moral obligation to those individuals who, legally or within the framework of manners, conventions, taboos, apparently have the strictest claim on one's loyalty?" Responsibility disrupts Ethan's studies and brings him back to the farm to care for his parents. His marriage to Zeena is marked by self-sacrifice, with Zeena deriving her "one pleasure ... [from] inflict[ing] pain on him." Towards the novel's end, it is this sense of duty that stops Ethan from asking the Hales for money to escape with Mattie. He convinces himself that the reality is he is a poor man, "the husband of a sickly woman, whom his desertion would leave alone and destitute." Critics have debated whether Ethan's decisions are guided by moral principles or by necessity and expedience. Lionel Trilling argued, "Choice is incompatible with [Ethan's] idea of his existence; he can only elect to die," while K. R. Shrinivasa Iyengar suggested, "It would be an oversimplification to say that the chief characters in Ethan Frome are only moved by blind necessity." Marius Bewley interpreted Ethan's choice to die with Mattie as a moral decision that "entails tragic consequences because it is the wrong decision."

Loneliness
The theme of loneliness is prevalent throughout the novel. At the beginning, the narrator observes about Ethan Frome, "I simply felt that he lived in a depth of moral isolation too remote for casual access, and I had the sense that his loneliness was not merely the result of his personal plight, tragic as I guessed that to be, but had in it, as Harmon Gow had hinted, the profound accumulated cold of many Starkfield winters." Ethan's house is described as "one of those lonely New England farm-houses that make the landscape lonelier." The advent of the railroad reduced local traffic, a change that Ethan's mother never understood. "It preyed on her right along till she died," Ethan tells the narrator. As his mother's dementia worsens, she becomes so silent that Ethan pleads with her to "say something." It is his fear of being left alone on the farm after his mother's death that drives him to marry Zeena. When Mattie first arrives to live with the Fromes, Zeena encourages her to seek out diversions, believing it was "thought best... not to let her feel too sharp a contrast between the life she had left and the isolation of a Starkfield farm."