People in general have a rather twisted view on what a pole hole is because of bad current views on what watching a movie is.
Is it disappointing they didn't end up detailing Joe's girlfriend? Absolutely
Is it a plot hole? Absolutely not. The character who doesn't functionally exist in view of the audience, and is basically there as a recurring gag is pretty standard. It's neither a plot hole nor forgotten.
Very little is actually forgotten in tri., things simply aren't used the way some fans want.