What is the only problem Blakeslee had with Mattie Lou?

The only problem Blakeslee had with Mattie Lou was that she never gave him a son.
According to the story, Blakeslee had always loved his wife. Yet, it saddened him that she never gave him a son.
Aside from this one "fault," Blakeslee thought his wife was perfect. The narrator gives us possible reasons for this. Miss Mattie Lou (as her husband called her) was a refined woman. She never read Greek or Latin and certainly never engaged in intellectual pursuits. However, she always treated everyone kindly and never patronized those who were her social inferiors.
When she was alive, Mattie Lou never fussed at her husband for not having their house wired for electricity. She remained patient, even after their neighbors wired their own houses for electricity. Mattie Lou continued to trim wicks, clean out dirty chimneys, and "fool with kerosene" when other ladies pulled a ceiling cord to get electricity.
Mattie Lou also refrained from complaining when Blakeslee refused to pay to hook up their house to the new water main and sewer system. She continued to draw well water and empty slop jars. It never seemed to faze Mattie Lou that she had no faucets or flushing toilets. If she was unhappy about Blakeslee's strange ways, no one knew about it. The narrator notes Mattie Lou's gracious temperament and hints that this is the likely reason Blakeslee worshiped his wife when she was alive.