Yeah, I really hated the ending. Really, really hated it. No doubt it's realistic to some extent, but it's not like anyone needs to tell us that, especially in a way that comes down to "just submit".
The message, in the end, turned out to be something like: "It's easier to live off part-time jobs in Tokyo than in the boondocks."
Which I suspect is something everyone and their uncle knew already.
There's a fuckton of otaku guys in Tokyo who work small part-time jobs and make enough to pay for food, rent, manga, doujinshi, anime merchandise, whatever shit they want. So yeah, we know it's feasible. Otoh on a sparsely populated island it's obviously gonna be more difficult to find a conventient arubaito. They lucked out when they were hired at that diving place; they ran out of luck after that.
So yeah, it's realistic, but... damn, I wish they had toned down the angst. ( ͡ಠ ʖ̯ ͡ಠ)
(And what the hell has the marriage certificate to do with their problems, anyway? It's not because of that that couldn't get jobs. Was it really necessary to tear it up?)