There is no possible way to make everyone happy. Even if Eternum had no sexual content at all, it would still be difficult balancing content out with all 6 love interests. Now we not only have 6 love interests intended to receive equal attention, we also need to pace sexual intimacy for them, which forcefully pulls relationship development along with it.
It's 7 actually*...
-Annie
-Nancy
-Dalia
-Penelope
-Luna
-Alex
-Nova
...
though it could still go up to 8 if Calypso ends up being a hidden main LI that gets unlocked once we reach a certain point in the story.
(*Unless that wasn't a joke and there's someone on the list that you're not counting as part of the harem)
But yes, the way Caribdis tied LI progression to the main story and the fact that there's too many of them (which necessitates to rotate through 3-4 at a time per update) is why their progression feels accelerated compared to OIAL where the main focus is actually on the first 4 girls that were introduced right from the start (Judie, Lauren, Carla, Rebecca) while the others (Iris**, Jasmine, Aiko) are just filler that are just there to increase scenes rather than add anything substantial to the story (and yes, I say this even knowing that Aiko basically saved our bacon during the Japan trip...but after that she was just kinda...there).
**This one hurts because she's the one whose design I kinda liked the most, but I stand by what I said
It's also why the time skips are necessary because of the plot-first nature of it all. Had it been the other way around (romantic progression over main story progression yet still keeping both tied for chronological reasons), I can already see the same people complaining that this update did nothing from a story perspective (which is objectively wrong because stuff still did kinda happen) to also complain when we get 2-3 updates of nothing happening but LI progression (which again, was what happened with OIAL 0.1-0.4 for the most part, with 0.3 being the only update where major plot progress actually happened).
DPC of Being a DIK is a massive jerk, but I greatly respect him for openly telling the playerbase to go fuck themselves before he changes a single thing about how he writes his story for them. Not saying that Caribdis does, but the point is that customers do NOT know what they actually want, and they will even lie about it.
Personally I think Caribdis also shares some blame. He didn't had to hype that Eternum was going to be bigger and better compared to OIAL, but he did (even did so at the end credits of OIAL). And the only way to say that Eternum is indeed "bigger and better" is to up the ante when it comes to LI focus (no more "only focus on 4 main and keep the rest as side hoes," now ALL of the 7 main LI's are going to get focus), main story (length is certainly longer this time around, and the writing seems to have more thought put into it other than "there's an evil cult trying to summon a demon who seeks to - you guessed it -
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and only an almost-failure of a student and his ridiculously attractive stepsisters (sisters if you install the incest patch) are the only ones who could stop them"), and overall quality (switch from HS1 to HS2 renders, area navigation segments actually feeling like area navigation and not "choose where you want to go from this list bitch," ACTUAL FUCKING MUSIC being used in scenes).
To his credit though, he succeeds for the most part in keeping his promise (IMO, some people might disagree) so not much complaints really. Though it would be nice if his next game is a bit less on the grand scale and something that's more localized ala OIAL (though with the lessons learned and the lore revealed for this game utilized to great effect in said next game). Maybe also cut back on the number of LIs in favor of fleshing them out more, that sort of thing.
I hope for Caribdis's next game he gets out of marketing in the "adult" genre entirely and goes more mainstream. No more obligations to pushing sexual activity to a certain level by a certain time, no obligations for perfectly balancing love interest time out of "fairness" to different fans. I'd love to see what he can do artistically with no restrictions.
I wouldn't go that far, personally. It would be a sad day (and I mean a VERY sad day) once Caribdis abandons or retires from the Western Adult VN market the same way that former writers/devs of the same genre on the JP side did (looking at you, Type-Moon and Nitroplus). In fact I think that's what drove me to check out the indie WEG (Western Erotic Games) scene in the first place because the JP side no longer cares in making the next "Saya no Uta" or the next "Grisaia" or the next "Fullmetal Daemon Muramasa." Whatever's left there is either Nukige or Highschool Romance schlock or NTR. And if you want the interesting stuff (story-wise) you'll have to jump ship to the Non-Eroge section. Or pray that localizers actually pick up something that's reminiscent of the old-school Adult VNs of old (which they won't).
Shit's depressing, really.