Is that an early ending where the dev didn't bother to make it an actual route, or will it lead to a lot more story?
80-90% of the game is dedicated to the NTR, such as it is. Basically, early on, you get a "to cheat or not to cheat" type of choice, though not specifically called out as such depending on perspective and whatnot. If the choice is "not to cheat", this leads to the ending where Sophie stays with Felix and they have a cute kid together. There's some consequences to the choice, but nothing sexual or that they can't otherwise overcome. It's extremely short.
If the choice is "to cheat", this leads to the majority of the story, where a variety of choices lead to several other endings that are various ranges of terrible when it comes to what happens to Felix. None of them are ever genuinely good, though he may not necessarily be aware of this in a number of them. Things turns out well in the majority of the endings for Sophie herself, except for one single ending, which is quite frankly the worst written of the lot. (By that point, it's pretty clear that Azienda was running out of steam in general since the endings on that branch in general are not great...)
At the end of the day, this is a NTR focused VN, and the majority of it is focused on said NTR. If Felix and Sophie both act like reasonable adults which stick to their principles and all that jazz, there's obviously not going to be much of a story and the team clearly had no interest in vanilla content.