There are two main reasons for the McCaskey couple's normal quarrals.
The first one, they had no kids, but we can know from the story that Mrs. McCaskey was eager to have one but they can't. Therefore, she was angry at her husbandwhen he showed indifference at the boy's missing news. Sometimes, old people's saying is right that children are bond for couples when they've been married for several years.
Apart from that, we can also see from the accent that Mr. O Henry described that Mrs. and Mr. McCaskey were low-class in the society and they were somewhat illiterate, which was one of the biggest problem for Mrs. McCaskey‘s temper. She had no idea what to do for her own life, so she devoted herself all in to the care for his husband. She wanted care from his spouse, but Mr. McCaskey was such a rough man that he couldn't feel the needs of his wife.
