Who had introduced them?
The Addisons, of course.

But the Addisons were socially unassailable, if not all-powerful, and so the best had to be made of that.

But the Cowperwoods could be dropped from the lists of herself and her friends instantly, and that was now done.

A sudden slump in their social significance began to manifest itself, though not so swiftly but what for the time being it was slightly deceptive.
The first evidence of change which Aileen observed was when the customary cards and invitations for receptions and the like, which had come to them quite freely of late, began to decline sharply in number, and when the guests to her own Wednesday afternoons, which rather prematurely she had ventured to establish, became a mere negligible handful.

At first she could not understand this, not being willing to believe that, following so soon upon her apparent triumph as a hostess in her own home, there could be so marked a decline in her local importance.