Symbolism, Imagery, Allegory
When Archer tells Madame Olenska that he wants to live with her in a world where categories such as "married" or "adulterer" don't matter, she responds, "Oh my dear —where is that country?" (29.55-56). Archer and Madame Olenska's relationship develops in spaces far from the drawing rooms and opera houses that occupy the center of New York society. Their first meetings alone are in Madame Olenska's home in an unfashionable, "bohemian" section of town. From what we can tell, this place is bohemian because it's not super-duper rich. It's just pretty rich.
Subsequently, Archer will seek out Madame Olenska in an abandoned cottage on the van der Luydens' estate, at the Blenkers' vacation home far from where the rest of society vacations in Rhode Island, and Boston, where they take a ship out to a remote point to have lunch alone together. They meet in abandoned museum galleries, train stations, even for brief moments on the street. These locales underscore the fact that Archer and Madame Olenska's relationship isn't condoned by the rest of society.
Archer and Madame Olenska are hardly meeting in seedy motels or dark bars, though. Vacation homes, cute lunch nooks and museums don't exactly constitute "shady." They're just shady to the members of New York society. It's telling that the first place they have something that might constitute an illicit rendezvous is in the second (yes, second) of the van der Luyden's homes on the same plot of land. Oooh, deviant.
Because Edith Wharton is a genius writer, she doesn't stop at these "weird" houses simply symbolizing illicit behavior. They also symbolize how this behavior is only really illicit, or scandalous, in the context of this New York society. Sure, no woman would be thrilled if her fiancée left her for her cousin. Way understandable. But is that worth complete social banishment? Would it break lives irreparably, forever?
In societies less rigid than this particular New York circle in the 1870s, nope. It would be no more an act of utter society-is-going-to-melt-down-level-destruction than, say, your weird Uncle Bob throwing the Thanksgiving turkey on Grandma Rose's white carpet, again.