Personal fulfilment versus marital, familial and social duty
By making Mattie and Zeena so different, in that all the life, beauty and energy are given to Mattie, and all the deathly and sickly qualities are given to Zeena, Wharton makes Ethan's choice clear-cut. When it comes to Ethan's feelings, he does not waver. He loves Mattie and comes to hate Zeena, but his sense of duty to Zeena prevents him from acting decisively to be with Mattie. His entire relationship with Mattie is conducted under the shadow of Zeena and thus is restricted to little more than the furtive holding of hands. Even when Zeena goes away, her presence looms between the lovers in the form of spectral visions and the cat. Finally, as he sees it, his duty to his wife and to the Hales prevents him from asking the Hales for money to elope with Mattie. He gives as his chief reason for inaction the fact that he is "the husband of a sickly woman, whom his desertion would leave alone and destitute."
As well as sacrificing love, Ethan also sacrifices his interests and ambitions to look after others. He breaks off from his studies to care for his father and mother, and fails to move back into a town to study and work as an engineer because of Zeena's illness.
Ethan never finds the courage to commit to either personal fulfilment or duty. He opts out of the dilemma by opting for suicide with Mattie. Denied even this outcome, he ends up in an uncomfortable mnage trois with wife and lover, his lover having turned into a version of his wife. The forces of marital and social duty triumph over Ethan and Mattie, two people who were not strong enough to defy them.
Ethan Frome is a study in frustrated desire and ambition. Ethan fails to fulfil any of his ambitions - to move to a town, become an engineer, or run away with Mattie. He finds it difficult to express himself, being as frozen in character as the winter landscape. In Chapter 2, he searches for "a dazzling phrase" to impress Mattie, but nothing comes to mind and he can only "growl," "Come along."
Because he is unable to act decisively enough to change the trajectory of his life, he gives himself over to fantasy and daydreaming. Daydreams become the only outlet for his hopes. When he returns with Mattie to the farmhouse, he sees a dead vine hanging from the door like a crepe streamer tied to the door as a sign that someone within has died, and has the thought, "If it was there for Zeena -". His response is striking for its similarity to the whims of children, who are helpless to change their lives and so are much given to wishing that inconvenient people were dead. From an adult such as Ethan, we expect more resoluteness, but in vain. It never comes.
Zeena too finds that marriage does not live up to her expectations: as she thinks, Ethan does not listen, and so she has given up talking. The unused red pickle dish is a symbol of the sexual and emotional frustration of their marriage.
Wharton contrasts the vitality of the climate, with its blazing blue skies and glittering white snow, with "the deadness of the community". Far from making the residents lively, the atmosphere only seems to retard even more "the sluggish pulse of Starkfield". Indeed, it is as if nature declares war on Starkfield during the winter and forces the community into surrender, as is emphasized by Wharton's use of military metaphors: "the storms of February had pitched their white tents. and the wild cavalry of March winds had charged down to their support; I began to understand why Starkfield emerged from its six months' siege like a starved garrison capitulating without quarter."
The theme of winter is linked with Ethan himself in the image of his shed roof sagging under the weight of snow. Harmon Gow says Ethan Frome has been in Starkfield "too many winters." The narrator describes the Starkfield winter as the negation of life: ".when winter shut down on Starkfield, and the village lay under a sheet of snow perpetually renewed from the pale skies, I began to see what life there - or rather its negation - must have been in Ethan Frome's young manhood."
The frozenness, isolation and rigidity of winter is symbolic of Ethan's deadened and defeated vitality. It is significant that he only marries Zeena to avoid spending a winter alone in the farmhouse after his mother's death, a tactic that fails when she too falls silent and the marriage becomes buried under a 'snow' of indifference and lack of communication.
In contrast, Mattie is referred to in images of spring, life and warmth: ".the coming to his house of a bit of hopeful young life was like the lighting of a fire on a cold hearth." Her expressiveness contrasts with Ethan's frozen inarticulateness when trying to tell her of his feelings.
But Mattie's warmth fails to penetrate Ethan's winter. Even his fantasies of being with her involve death, as when he asks his dead ancestors to help him keep her on the farm. He is able to share joyfully in Mattie's warmth of character, but ultimately he is unable to rise to her level of life. Ethan (and the force of the long Starkfield winters) ends up bringing her down to his own level of frozen sterility.
Illness and disability
Ethan Frome's ambitions are defeated by having to look after a series of invalids - his father, then his mother, and then his hypochondriacal wife Zeena. Zeena uses her illness like a true professional, to manipulate Ethan and others. She is able to bring Mattie into the house to release herself from household duties, and when she begins to see Mattie as a rival, she forces Ethan to agree to pay for a hired girl to replace her.
Illness appears to be a common phenomenon in Starkfield, with most people having "troubles." But only a chosen few, "singled out for a great fate," have "complications" - a label which often translates as a death-warrant. After her visit to the new doctor, Zeena claims to be one of the "chosen" ones with "complications." She confers upon herself the special status of martyr. No longer whiny and reproachful, Zeena gains a sense of purpose that eludes Ethan. Her illness becomes a weapon that she uses to take control of the household. She is successful in having Mattie sent away. Although very soon after, the crippled Mattie is brought back to the house, Zeena perfects her dominance by miraculously regaining her health and caring for her former rival, who takes Zeena's place as the invalid. Ethan himself is disabled by the accident, making it less likely than ever that he will make a success of his life.
One of the ironies of Ethan Frome is that the character who is meant to be the invalid - Zeena - is the one who most ruthlessly wields power. The character who is, for most of the novel, strong and healthy - Ethan - is unable to assert his own will. He submits first to Zeena's will, then to Mattie's (the suicide pact) before ending up once again under the domination of Zeena.
Irony pervades Ethan Frome, in the sense that the natural, expected outcome of every incident is subverted: the worst possible thing happens each time. Ethan should be a successful engineer, but after he breaks off his studies to care for his parents, he must settle for farming, for which he has neither inclination nor especial talent. Ethan and Mattie's first evening together should be a romantic idyll, but descends into distress after the pickle dish is broken. During this evening, Zeena should be absent at the doctor's, but the cat acts as her 'agent' and comes between Ethan and Mattie.
The most terrible irony is the failed suicide pact. Instead of being united in glorious death, Ethan and Mattie are crippled and sentenced to living with Zeena forever.