The best way to answer this question is, perhaps, by rephrasing it. A suggestion for this would be: “How would Mattie’s death influence Ethan’s life?”, or “Would Mattie’s death make a difference in the rest of Ethan’s life?” The reason for this suggestion is because, in reality, someone’s death does not really make anyone’s life “better off,” especially when it is the death of someone who is loved and cherished. Had Mattie been abusive or cruel to Ethan on a daily basis, perhaps her disappearance from his life would have given him a chance to start over and heal.
Yet, Mattie is Ethan’s object of affection. In her, he sees all the joy and joviality that had been lost in his wife Zeena for years. Mattie symbolizes a degree of hope in the life of Ethan Frome. There is no other symbol of hope in his life.
This being said, let’s now answer the question: How would have Mattie’s death influenced the rest of Ethan’s life?
First, in the words of William Shakespeare in Richard II
Grief makes one hour ten
This means that the sadness that Ethan would experience for the loss of Mattie would be of such magnitude that he will likely never stop thinking about her. His feelings for her are likely to intensify, and this will make his marriage to Zeena all the more unbearable. That is definitely not a sign of being better off.
Moreover, if Ethan idealizes a near-perfect life with Mattie while she is alive, the chances are higher that he will idealize her at a much greater magnitude after her death, thinking about all the things that could have happened if only he had done things differently.
Furthermore, Ethan would have had to live with the guilt of knowing that he was there at the moment of Mattie’s death, and that he consented to the ridiculous plan of committing a double suicide by sledding down the hill to crash against the big tree. Imagine looking back upon that particular event and remembering forever that you were a part of the idea!
The only think that would have made Ethan’s life better off is working proactively to defeat his fear of loneliness. If he had learned not to depend on his environment to feel accompanied, and if he had learned to appreciate the solitude and the silence that enveloped his life at the time of his mother’s illness and death (that he hated so much), he would have seen them as venues through which he could have learned more about who he is. Instead, he succumbed to the environment and used people, voices, and words as signs of companionship.
He could have learned to be alone without feeling lonely. He could have waited until the deaded winter season which he detested so much passed, and after his grief for his mother had also passed, to search for his better half when he was good and ready. Yet, in Ethan, we see a deeply flawed character who acts impulsively for things that he could have waited for. Conversely, he also wastes his time neglecting things that he needs to act upon quickly, such as the communication with Zeena, or the need to change his life.
In all, Mattie’s death, or even her life, for that matter, would make no difference in the life of Ethan Frome. He is destined to be unhappy because he refuses to take the risks that would bring changes in his life. The only risk that he took was the most asinine one: Trying to take his life. He could not even do that.