After her marriage to Edward Maitland Armstrong, Gwendolen occupied herself with many community activities. She became what Vogue magazine referred to as the "new young woman about town.” Gwendolen joined a women's basketball league, was active in the Red Cross, organized outings, and skating parties, and helped found a country day school, which her children attended. She would often travel by train to New York City to visit and lunch with friends, shop at department stores, visit galleries and museums, and attend afternoon concerts. Subtle changes in her clothing styles reflect her new bustling schedule.

Gwendolen seemed most at ease in casual clothing, such as shirtwaists and serge walking skirts, or tailor-made walking and traveling suits. Gwendolen's changing tastes put her in the company of young women such as those described by dress historian Patricia Cunningham:

"In the second half of the nineteenth century and early twentieth century it was no longer enough to look modern by adopting the latest fashion; many women now wanted to be modern. These women desired simple, healthful, practical clothing that would allow them to be active participants in the public, professional, and economic arenas of society, but fashion and its accompanying rules for behavior were tenacious."

Fashion and its accompanying rules for behavior were indeed tenacious and complex. Gwendolen's change in style was influenced and compounded by a number of important factors. While difficult to surmise exactly, her change in financial circumstances, the influence of her free-spirited and artistic in-laws as well as larger social changes are probably all responsible for her changing tastes.

After settling on Long Island, Edward Maitland Armstrong took a position at a landscape architecture firm in New York City. By 1900, the King and Armstrong families, while rich in intellect and talent, had diminished financial means and were struggling to keep up with an ever changing economy. The real estate and China Trade-derived "old money" which had once provided a very high standard of living was easily surpassed by large industrial fortunes of the last decades of the 19th-century. Gwendolen and Edward found themselves living a more modest lifestyle. Gwendolen no longer traveled annually to Paris but benefited from her mother's trips and those of her circle of acquaintances. She writes to her mother in 1911:

"I have just decided to buy a tea gown from Pauline Wagstaff! The way of it is this. It was sent over to Elsie Vanderbilt from Paris, she did not think it becoming and sent it as a present to Pauline. Pauline found it—too small and unbecoming and offered it to Una for $25.—She was going to take it and have it made into an evening dress but as I liked it” tel que” she let me take it! So I thought I might as well as it is such a bargain and just what I wanted and you can bring me something else instead!... I hope you think I was wise to take it as it is really very pretty and must have cost a great deal more.”

Gwendolen's mother, Ella, maintained her preference for European-made couture fashions and viewed American department stores and the assortment of ready-made goods available by the early 20th century not as a matter of convenience, but as simply beneath her. Ella continued to travel annually to Europe to buy European-made clothing as she felt it was indicative of her upper class status. Ella was not concerned with embracing modernity, but strived to maintain a lifestyle that was a complement to her reserved temperament and Victorian conceptions of modesty and propriety.

Ella's views are evident in the following, she writes:

"I have a hat for you, which I hope you will rather like…if the shape suits you I think it’s a hat you can wear a great deal. I daresay one can get nice readymade clothes, but I have never had any…”