Perhaps tag this as a kinetic as no matter what you do or choose Oliver and Amanda still have sex behind your back as they apparently have been doing all along further humiliating you.
That aside, the OP says multiple endings are planned. Calling it a kinetic novel means that there are no choices, and you're just reading a story. The fact that multiple endings are planned would negate the tag of "kinetic novel." Yes, there were no real deviations in this first update, but that doesn't mean future updates won't have different choices and outcomes. First updates tend to not have many choices, so this isn't new.
Anyway, a couple of things I read in other people's comments. Yes, this is definitely NTR. MC is obsessed with Amanda, and she's hooking up with Oliver behind his back. That's NTR. NTR is different from cheating and cucking. The MC doesn't need to be in a relationship for it to be NTR. And MC is definitely being betrayed by Amanda. If he were to find out, he'll flip out or be devastated.
With that being said, I liked this first update. I think the set up is interesting, and it gives the potential for a lot of hijinks to happen during the party. I wouldn't recommend rewriting the intro (ie, removing the NTR since 90% of time, "rewriting" is another way of saying removing NTR). NTR haters have already blacklisted the game. Even if you go back and remove every trace of NTR, they won't be coming back to support the game. I haven't seen a game on this site remove NTR introduced in the first update, and then draw back in those people they hoped to salvage. Stick to your original outline. Besides, NTR haters have a ton of options out there, way more than NTR lovers or people neutral to NTR. And we don't have enough NTR redemption stories. I want to see MC start of at a low point, but grow to become a man that gets all the ladies (or possibly fails along the way, as an alternate route).
The ultimate determining factor for a game's success is the quality. If it's good, it'll be successful. Just focus on creating quality work and the support will come. And don't try to appease everyone.
P.S.: If there is ANY thing I really didn't like about the update, it was having to choose between punching Sadie, or getting a BJ from her and pissing off Amanda. I feel like you shouldn't have to punch her to avoid that outcome. Speaking of which, whether you get a BJ or not, Amanda still acts pissed at you as if she caught you hooking up with Sadie. That seems like a mistake.