Ok, so I was thinking about the like "narrative reason" for Hal's memory loss this time and here are my dumb thoughts.
So, my original thoughts were like "didn't he already learn to control his memory loss in Air Poker? It feels like we are treading old ground/regressing on his development."
But thinking about it more,
In Air Poker, Hal faced the shadowy Hal and regained his memories for the purpose of being perfect (as he realized he needs them to be perfect). So Hal overcame the feeling of needing to start over if he fucks up, but in turn his obsession with perfection got worse. Honestly I feel like this game he had more pressure put on him, as instead of "becoming perfect," it's "staying perfect". And Hal's obsession with perfection (obviously) seems pretty unhealthy.
Hal even gave his speech about how "it's impossible for humans to be perfect, but I'm different because I'm an alien." But Hal too is unable to stay perfect and eventually he has to face that fact. So I feel like that is what is being communicated through this memory wipe (ok well it might be obvious based on some of the text, idk). And I'm assuming that by the end Hal will realize he doesn't need to be perfect (as that would seem like the natural course for that sort of character flaw). And the memory wipe may play a part in that realization too.
Anyway, the cube with all of Hal's friends/special memories, and the imagery of him crumbling is so tragically beautiful ;_;
And I wonder which memories this Hal has.... Good that he's not a husk of a man, like I considered would happen if he lost his memory, last chapter, lol.