And so it all ends with one final Mitt Romney flip-flop.

Having thrust his way back into the 2016 Republican presidential sweepstakes three weeks ago by letting us know that, despite long months of ruling it out, he really did want to wage a third campaign for president, Romney has now decided he won’t run after all.

That’s a smart decision and, I have to admit, one I’m surprised he made.

After all, we had already started hearing the usual Romney pre-campaign claptrap.

To wit: He and Ann were convinced he’d make the best president of anyone in the GOP field. (It’s hard to say which of the two is more enamored of Mitt and his putative abilities.)

And given that, they thought he had a duty to the country to run.

Mitt, of course, always likes to couch his personal ambitions in patriotic terms, even though only he and a handful of acolytes truly believe that blather.

Brush aside the usual justifications, and what was obviously driving his latest presidential exploration was ego, ambition, and a desire for redemption.

A man who thinks his own superiority is self-evident, Romney was surprised to get beaten — no, thumped — by Barack Obama in 2012.

He didn’t want his political career to end on that sour note. And he clearly thought the country was having second thoughts, that it wanted a do-over.

Make no mistake, that kind of notion is important to Romney. Some months after his 1994 U.S. Senate loss to Ted Kennedy, I had lunch with him.

He had taken a post-election poll, Romney told me, and it revealed that if Massachusetts voters had known the Republicans would take over Congress in the midterms, they would have elected him rather than reelecting Kennedy.

His self-esteem badly bruised by his loss, Romney took real solace in that supposed sentiment.

For my part, I was surprised he would spend good money on that kind of ego-massage. However, this latest episode brought to mind that post-election vanity project of two decades past.

Except that this time, there won’t be another run.

Romney could point to surveys showing that Republican voters were receptive to seeing him try again for the presidency; that said, early polls often show residual support for a party’s last nominee.

But he just as clearly misjudged the mood of the Republican establishment.

Mitt likes to style himself as a white knight reluctantly responding to repeated urgings that he ride to the rescue.

Yet when he made it known that he was thinking of running again, the reaction he got from GOP’s officeholders, graybeards, and stalwarts didn’t buttress his preferred story-line.

Instead, it was basically this:

Nice guy, but he had his chance and he blew it, and now it’s time to move on.

And now, apparently, both the Republican Party and Romney will.

Which is the best course for both of them.

Scot Lehigh is a columnist for The Boston Globe.