There is much in way of an idyllic domestic setting revealed in the first paragraph. Dahl explores the basic conventional notion of domestic life in the opening paragraph. The "warm and clean" descriptor reveals that Mary has tended to house very well and that the home is the embodiment of domesticity. The table lamps and the chair that has been tended for Patrick who is coming home after a hard day of work. Mary has tended this area for Patrick. It has been curated and tended to such a degree that the "Fresh ice cubes in the Thermos bucket" reflects how Mary anticipates Patrick needing a drink after work.
The opening paragraph suggests that Mary tends to home and husband in a very diligent manner. It is evident that she believes in the authenticity of their marriage and her role in it. While Patrick has been contemplating leaving the marriage for some time, it is obvious through the description of the home that Mary does not see anything wrong in the marriage. She has tended to what she believes to be her responsibility and her duty at such an intense level that she is legitimately surprised by his disclosure. In waiting for her husband, Mary shows that she believes this marriage to be worthwhile and something that she accepts. One can see that in the way she tended house Mary believed in the authenticity of her relationship with her husband.