Are you thinking of irony?
Irony is when the opposite of what you would expect to happen actually happens. A firehouse burning down to the ground is ironic because you would never expect that to happen.
the opposite of "happen" is "dematerialize"
That concept is known as irony. It involves a discrepancy between expectation and reality, often manifesting in a situation that is the opposite of what one would expect.
That would be irony! (Situational irony, if you wish to be more specific.)
Nothing Expect it. Expect us.
irony
well what do you expect. "For every action, there is an equal or opposite reaction." There is subtraction, and the opposite is addition.
The one word that can be an antonym of both is accidental.
Well, I can tell you that the opposite of happen is spelled in two ways: 1) Dematerialize or 2) Dematerialise.
The opposite of "didn't happen" is "did happen." While "didn't happen" indicates that an event or action did not occur, "did happen" confirms that it took place. These phrases represent contrasting outcomes regarding the occurrence of an event.
The opposite of "expected" would be "unexpected" or related words such as surprising, unanticipated, or unforeseen.
Irony