Having lost badly to Hillary Clinton in their first debate, Donald Trump has turned to a subject on which he can claim expertise: having affairs.

Not his own, in this case, but Bill Clinton’s sexual indiscretions, which he is attempting to hang around Hillary’s neck. The logistical challenge is obvious: Most of the world regards the betrayed wife not as the cheater but as the cheated upon.

Trump’s workaround is to portray Hillary as an “enabler” who knew all about Bill’s various affairs. He contends that contrary to the feminist code, she attacked the women Bill consorted with.

Let’s dispose of the first rap and greatly reduce the charges on the second. Hillary did not enable her husband’s extramarital activities — any more than Eleanor Roosevelt enabled Franklin’s or Jacqueline Kennedy enabled John’s.

Of course Hillary knew that her husband fooled around. So did Eleanor and Jackie. Eleanor actually suggested divorce. Franklin D. Roosevelt’s mother would have none of it. She threatened to cut her son from his inheritance if he didn’t give up his liaison with Lucy Mercer, which he didn’t. Eleanor nevertheless went on to champion great causes, and FDR remains one of America’s most revered leaders.

John F. Kennedy’s sexual adventures were probably far more numerous than Bill Clinton’s and definitely more dangerous. One of JFK’s women was a party girl with mob ties, and another widely regarded as a spy for communist East Germany. Despite it all, Jackie genuinely grieved for John after his untimely death.

None of these first ladies condoned her husband’s wanderings. They endured them. And their marriages went on.

In the older moral tradition, adultery was a matter for adults to work out among themselves. But divorce hurt children. Thus, divorce also wrecked political careers.

In 1963, former Sen. Prescott Bush (George W.’s grandfather) refused to back the presidential candidacy of his friend New York Gov. Nelson Rockefeller over divorce. “Have we come to the point where a governor can desert his wife and children?” Bush fulminated.

A married man who paraded publicly with his mistress, as Trump has done, inhabited an entirely lower category of scoundrel than the conventional sneak. Bill Clinton, for all his weaknesses, never intended his frolics to become public.

In a perfect world, Hillary would have withheld criticism of Bill’s trysting mates. But there are mitigating circumstances. A woman is entitled to dislike her husband’s paramours. And her reference to Gennifer Flowers as a “failed cabaret singer” came at a time when she genuinely did not believe the Flowers story.

In the case of Bill’s fling with Monica Lewinsky, more than a political career was at stake. The presidency was.

Hillary’s calling Lewinsky a “narcissistic looney tune” may have been overdoing it, but the first lady thought she was saying it in confidence to a friend.

It needs repeating that Bill Clinton’s partners were all consenting adults. Unsubstantiated claims that Clinton physically forced himself on women — or that Trump did the same — can be dismissed.

The real outrage of the Lewinsky frenzy was its paralyzing effect on Washington. Governance froze for months as Clinton’s tormentors danced around the maypole with Monica’s blue dress.

The American public eventually tired of the inquisition and turned on the inquisitors. Hillary’s popularity soared. In the next midterm election, Democrats actually gained seats in the House. At the end, Bill Clinton left office with a higher approval rating than did Ronald Reagan.

For all of Bill’s bad behavior, the Clintons appear to be a solidly married couple joined in political passion. Like Eleanor and Jackie before her, Hillary has been no partner in crime — and she’s not getting a divorce.

Froma Harrop is a syndicated columnist. Follow her on Twitter @FromaHarrop. She can be reached by email at: fharrop@gmail.com.