What are some of the universal truths shown in Edith Wharton's Ethan Frome?

One of the universal truths in Ethan Frome is the veracity of the saying "be careful what you wish for." Ethan wishes to remain by the side of his wife's cousin, Mattie, who he has fallen in love with, forever. At first, it seems like his desire will be thwarted, as his wife, Zeena, plans to send Mattie away. She knows Mattie and Ethan care for each other. In the end, however, Mattie and Ethan wind up spending their lives together, but there is an ironic twist of fate because Mattie is badly injured in a sledding accident. Mattie lives with Ethan and Zeena as an invalid, so Mattie and Ethan get their wish to live together forever, but not in the way they had imagined. 
Another universal truth expressed in this novel is the power of compassion. Ethan feels loyal and caring towards his sickly wife, so he feels conflicted about leaving her. He also feels compassionate towards Mattie, who has no visible means of support. In the end, Zeena is surprisingly compassionate towards Ethan and Mattie, as she cares for them after their sledding accident. In fact, it is her compassion for them that makes her well again after many years of being an invalid. Their mutual compassion is what keeps Ethan, Mattie, and Zeena alive and together, even after enduring tragedy.