Western Australian (or as Victorians unaffectionately call them, Sandgropers) don’t really act like they want to be in the same country as the more unwesterly states. I remember Dick Smith jams falling afoul of the Buy West Australian campaign, because their jams were bottled in Victoria.
And in 1933, they almost got their wish: Western Australian secession referendum, 1933.
What people don’t know (and I broadcast whenever WA comes up in conversation), is that the referendum passed.
It didn’t go anywhere, because like loyal British subjects, WA took the matter to London. And London had just passed the Statute of Westminster 1931, whereby Commonwealth countries could, like, run their own countries (“The main effect was the removal of the ability of the British parliament to legislate for the Dominions”). This made Western Australian secession Not London’s Problem.
Canberra (and Perth) had not ratified the Statute, and didn’t until 19-fricking-42; but Canberra was hardly likely to object to the outcome. The government that had proposed the referendum got voted out in the same election; so Perth didn’t care either. So the WA delegates sulked around London for a couple of years, and went back home.
EDIT: for a far better account, I direct you to the magisterial Carter Moore’s answer to What would have happened if Australia had been partitioned in 1933?