[ChicletPrime]

(i haven't met Sylus yet. But this came up in some kind of Hunt that required him as a companion so... yeah. HI SYLUS! ah-mazing first introduction. do you take all the ladies on these kinds of first dates just to break the ice or what?)

[Coldsaturn]

/inhales
daddy.

Am I understanding correctly that you're playing "Under Deepspace" and waiting to reach the end (chap 8) before you move on to "Long-awaited Reverly"?

Abyssal Chaos happens narratively once the MC has already started a romantic relationship with the LI. It will give important info on the worldbuilding etc, but if you happen to go "?" at some of the things you read or how they act with each other, it's because of that. It shouldn't be spoilery per se, after all the game itself gives you access to it, so at most you'll get certain hints that you'll contextualize later, but it might anticipate or reference the content of some cards that you'd have either pulled or watched on youtube for completionism.

[ChicletPrime]

I ... I honestly do not remember where I got this, but if you say it's from Under Deepspace I will believe you. I hit level 40 or 45 and something blinked at me so I clicked it, and there was this amazing layout of a bunch of tech buildings in wireframe and then it led me off on a merry little quest chain that told me to use Sylus as my companion for extra rewards.

We were rank 80, which was interesting and I got to about combat stage 11/20 before I stopped and said woah, maybe I should actually finish the main story first because this is going really good places visually and story wise and I do not in the least know what's actually happening or where this fits in (if it fits in at all).

I mean, Sylus is making all sorts of very interesting comments in my direction in this sideways time BUT I DON'T KNOW THE GUY YET. I felt like I was progressing too fast in a very unexpected direction.

[Coldsaturn]

The Main story chapters are divided in big sections. The first one, called "Under deepspace" is the one you start playing when you create the character (the one where she joins the hunters and you soon meet xavier etc.). That section has chapters that you can't unlock all at once. It usually takes around 2 weeks in order to complete it because it requires you to have a certain level (not the cards level, your MC level, for which you get exp by completing the daily tasks).
But way before you can finish Under Deepspace, another section will be offered to you just under it, called Long Awaited Revelry. This isn't a spoiler, but that's where you meet Sylus in the main story line. Because this section is open before you can complete Under Deepspace, many players jump ahead in the plot and then have to go back and finish the first section (under deepspace) in order to understand how we get to long-awaited reverly.
You might have accidentally followed the proper timeline by not jumping ahead lol

The tech buildings wireframe etc. is Abyssal Chaos (you access it from the Battle menu, not the Main Story menu), which opens up to you once you cross a certain level threshold, as you did. Every companion you choose for the two side missions available in there will be given to you using the cards you have, but at max level, max ranked, and ascended. It also makes sense in terms of plot that your companion is THAT powerful, because these side missions take place after the main storyline, so you and your companion of choice are already romantically involved at that point in time.
Whether Abyssal Chaos content can be considered spoilers if you haven't finished the main story line is debatable. On one hand, yes, you'll get many references about things you haven't discovered yet, so you might anticipate that revelation. On the other hand, it's possible that most of it will fly over your head and you'll still revisit it later on to organize your thoughts.

Let's go back to the Main Story menu for a second.
When you're in there and you see all the chapter progressions, if you look at the top right corner of the page you'll see the title of the section you're in. If you click on it, you'll see the other sections available. They go in order of plot, so if you jump ahead you might miss some links, but it's not the end of the world since you can just go back and retrace your steps.