The ending is about as ironic as things get. Zeena, once queen of hypochondria, is having to serve her maimed husband and his invalid could have been wife/mistress/girlfriend or something like that (this is an odd story!). As for deserving this? I suppose something had to happen to Zeena. She could not go on treating her husband like dishwater and charming every doctor in 200 miles to look at her ulcers. Actually serving the people she tormented sounds about right. As for Mattie and Ethan, the whole toboggan death pact thing was pretty ridiculous. They had other options (like leaving) and besides, if you really wanted to kill themselves, there were better ways to off themselves than smashing into a tree. In terms of stupidity I'd say they do deserve their fate. In terms of their very sad existence one kind of wish things turned out better for them. I'm not convinced there is any moral lesson to this. A lesson, as such, isn't the intent of this fiction. It is more an exploration odf character.