What is most upsetting to the family about the roof?

The most upsetting thing to the Luthers about the roof is that it wrecked their mother's rocking chair. That's a breaking point for Romey in that he lets his other sisters see him upset, and not just Mary Call. That's also when Mary Call wants to give up. Not only did it wreck a family heirloom, the collapse is threatening their safety and health this winter.