If anything, the attitude of the mother towards Paul in the middle section of this story is only exacerbated by the money that Paul wins for her through his secret gambling. If we consider the voices in the house that Paul hears to be indicative of the mother and her desperate desire for money to the exclusion of everything else, then it becomes clear that the middle section of this story only makes the mother more distant and more detached from Paul. Consider how the voices are described after the money is given to her and the response of the ubiquitous voices:
And yet the voices in the house, behind the sprays of mimosa and almond blossom, and from under the piles of iridescent cushioins, simply trilled and screamed in a sort of ecstasy: "There must be more money! Oh-h-h; there must be more money. Oh, now, now-w! Now-w-w--there must be more money!--more than ever! More than ever!"
The increasing volume of the voices corresponds with the "cold, hard" look that crosses Paul's mother's face when she reads the letter informing her about her money. The middle section of the story therefore represents a further worsening in the state of the relationship between Paul and his mother.