In it, she wrote, "An affair can last from one night to forever," a pretty clear sign that dating and sex could now go hand-in-hand.
Accessibility to the Pill, legal abortion and the rise of feminism made experimentation part of the "getting to know you" process and "Hooking up" is still very much a part of the courtship process, as anyone on Tinder knows, while formal dates do still happen.
This would continue on until a mutual interest was reached and a marriage proposal was offered.
There could be sexual tension involved, as anyone who's ever read Henry James knows; but the pace would be what we'd call today a (seriously) slow burn.
I collect old etiquette books in general, but hers have always been my favorite, mostly because she’s way crazier than the far more famous etiquette expert Emily Post and seems to have no idea that poor people exist. I have culled these delightful examples of outdated etiquette tips from both the 700-page tome “Amy Vanderbilt’s New Complete Book of Etiquette” and the slightly smaller advice column-style “Amy Vanderbilt’s Everyday Etiquette,” both published in 1952.