Yeah at this point dev gives up on the so-called midroad route, even if the status shows that the character is dating you they will still cheat if you don't disable NTR
What's weird is the first half path of the game is mostly determined by your answer to "Can i go after your family?" (sets $marcusbeta/$marcusalpha).
The second half is more determined by both:
1) Which version of day 26 you had (a simple question where "Visit Maude" stays on alpha path, "get a massage" takes you to the weird Emma coffee shop where you're on alpha path but she still references being with marcus)
2) Whether you had above 30 confidence going into drinking party night, which shows the threesome versus the guessing game.
*(Btw players really dont need a walkthrough, knowing these two facts above is enough to pretty much guide them through the playthrough they want)
The problem comes as you had mentioned that there really isn't a "mid" path, the "mid" path just turns into the ntr path (and a worse version of it with less content because you dont do the earlier spying options with James).
Seems like with very little work the dev could have a "mid" path, like one that requires both high confidence and high marcus_like or sophie_like score where you and marcus are kind of partners in crime, and divvy up the girls; e.g. "I'll take this one, you can have this one, and we'll double up on this one."