Why did Molly ask for a fur coat in "The Fur Coat"?

Molly's husband suggests that Molly might want a fur coat simply to keep her warm. Molly, half surprised at the suggestion, agrees that this might be a reason, but it is not her main reason. She says that her main reason is because they will be receiving lots of invitations "to parties and receptions and so forth," and she doesn't have anything suitable to wear.
Molly repeatedly denies that she wants a fur coat to show off, or "for grandeur," and insists that she wants a fur coat that she can wear "any old time." The fact that she repeatedly makes this denial suggests that perhaps she really does want a fur coat "for grandeur" but would prefer not to to believe that that was the reason. Her denials are really self-denials. This interpretation is supported by her reaction when her husband seems to believe the reason she gives for wanting a fur coat. She "lean(s) back, contented, with the air of a woman who ha(s) successfully laid her conscience to rest." The implication here is that her conscience knows why she really wants a fur coat, and feels shame for that reason.
Molly also pretends later that she wants a fur coat because it will be quicker to dress. "The beauty of a fur coat," she says, "is that you can just throw it on." She also continues to insist that she doesn't want a fur coat "for grandeur." She says to her husband, "I can assure you, Paddy, that I loathe—I simply loathe all this modern show-off."
In summary, then, the real reason Molly wants a fur coat is to show off and to look like a well-to-do woman. However, she is ashamed of wanting a fur coat for this reason and so pretends that she really wants it to keep warm, to fit in at parties, and to get dressed quicker.