Not only that, but the Articles of Confederation, which was replaced by the U.S. Constitution, contained the following:
”And that the articles thereof shall be inviolably observed by the states we respectively represent, and that the union shall be perpetual. “
There is no mention of “perpetual” in the U.S. Constitution.
And I’m sure that’s something that was debated in the Constitutional convention, if anyone wants to bother digging through those notes.