What a difference a generation makes. Today, few people seem the least bit concerned that Prince William and Kate Middleton, set to wed this month, have been living together off and on since their university days.

“We live in a modern age and people do all sorts of things before they settle down,” said Keith Morley, 34, an engineer from Birmingham. Some historians say it is about time the royals shed the prudishness they exhibited at the time of Diana’s marriage, which came years after the pill and the Summer of Love made casual sex more socially acceptable even in traditionally uptight Britain.

The modern-day tolerance of William and Middleton’s living arrangements, many say, just brings the House of Windsor in line with the times. Part of the change may have to do with the very public infidelities that played out in the disastrous marriage of Charles and Diana, which rocked the royal family to its core.

“After two decades of scandal, I think it is the royal family recognising that to be normal is to their advantage,” said Deborah Cohen, a historian at Northwestern University in Chicago.At the time of Diana’s engagement, the royal family and its advisers expected that she be a virgin, sparking dozens of speculative newspaper stories. It all prompted her late uncle, Lord Fermoy, to pronounce publicly that she was a “bona fide” virgin.

Practical concerns, more than squeamishness about sex, were behind the royal family’s historic concerns over the virginity of a prospective bride, Cohen said. There were fears that a princess could be carrying another man’s child, bringing an illegitimate heir to the throne. This was particularly important before paternity testing provided a scientific way to determine a child’s biological father.

By Diana’s time, Cohen said, the issue of virginity had come to represent a yearning for lost innocence as Britain was gripped by a perceived social breakdown driven home by its unwanted status of having Europe’s highest divorce rate.

“What began as a concern about legitimacy acquired all sort of connotations tied to social purity,” Cohen said. “Diana’s virginity became symbolic of the possibility of a return to an innocent past for everyone, and now we’re so past that, it’s laughable.”

In effect, that liberates the new royal couple to live their own lives without carrying such a heavy weight of society’s expectations.

They are not expected to adhere to an ideal that fell out of fashion several generations ago, long before Middleton sauntered down a charity fashion show runway wearing a transparent dress over black lingerie, producing photos that seem destined to live forever on the Internet.