And if it's not too much trouble, let me know what parts of the plot you didn't like. Feedback helps me improve.
To say "didn't like" is too strong, rather there were a few "so-so" moments. And even then, this is not about something objectively subject to criticism, i. e. plot holes or something, but rather related to a matter of taste, so it isn't necessary about "improvement", just to look at from different angle, perhaps.
Also keep in mind that I haven't completed available content in the current version yet.
1) You can interpret Jeffrey in many (not mutually exclusive) ways. In my case, it is either he is a complete idiot who can't figure out the true nature of Nicole even at the end of the first chapter (who is behaving as if not afraid of the mafia, even "forgetting" to track down Boris - Nicole relaxed too much to stick to the role in front of Jeffrey perhaps? Let alone the hotel worker scene), or a complete weak-willed wimp, or in absolute denial about his girl due to mental trauma and guilt complex. I prefer the latter option and it works relatively well, you can interpret Jeffrey like that.
Still, I'd prefer that he would be tormented by obvious doubts more clearly, yet suppressing them, to make it clear that he is not simply that naive, but is happy to be deceived. This is especially relevant for the more "brave" path where Jeffrey tries to oppose Jack.
In general, I like the idea of the main character being rather determined, with principles but too gallant with his lady for his own good... here the guilt complex is very suitable indeed. It was also fun to see how Nicole was irritated by untimely "noble" stubbornness of Jeffrey. Good laugh!
2) I'm not sure how Sam will enter the plot, but maybe the game shouldn't be overloaded with too many strong-willed girls. For me the main selling point of your game is how Nicole becomes mentally ill in the harsh M.A.N.S. world (at the same time poisoning Jeffrey's life as a collateral damage). But for that world to "shine", it shouldn't be overshadowed by too many dominating girls. I was sceptical about Elsa at first because of this, but now I think she is very suitable, because she also manipulates Nicole, which is extremely fun thing to see. But I'm not sure if the third character like this would fit in as well.