Wiktionary
n. (context rare English) A happening that fails to occur; a nonevent. vb. (present participle of unhappen English)
Usage examples of "unhappening".
So the first time I unhappened you, at the time of the kiss, I lost the ability to wipe out the rest of the interaction, because that would unhappen the first unhappening.
Princess Ivy listened to them, then watched the replay of the unhappening on the Magic Tapestry.
She was seeing an unhappening happening, for the first time, maybe because it was a big enough one to require extra effort.
So he did not feel as good about that particular unhappening as usual.
He could do so, because it postdated his last unhappening of the girl Becka.
There is a man called the Dastard who is going around unhappening events.
She knew these unhappenings had to be brief, because the Dastard didn't like to stay long in the past.
Becka suggested, not wishing the mischief of unhappening on anyone, even a troll.
The truth was that the notion of a really significant unhappening excited him almost as much as the prospect of marrying a lovely princess.
But the temptation of a really big unhappening prevented him from acting just yet.
Yet the Hag had remembered the prior unhappening, when the village disappeared.
But that would neither free it of the Possession by the Sea Hag, nor stop the Dastard from unhappening this event.
Had he done a partial unhappening, only enough to prevent the princess from flying away?
She didn't know how far the Hag had caught on about the several unhappenings, and didn't want to tip her off if she didn't know.
They had already stopped him from unhappening the unPossession, which had surely been the trickiest aspect of this contest.