Thank you for the explanation. I think the MMC will have the possibility of facing the threat of NTR. However, this might happen with his other love interests (not with the FMC). That's my current assumption. The script is written, but I haven't detailed it or planned alternative paths yet. As for the relationship between the main characters, it's actually a good idea. Unfortunately, it would break the game (resulting in a constant damsel in distress scenario), although it might be possible in the endgame.
P.S. I actually wanted to add the option to play as only one character, either Dutch or Kate (with the other on autopilot). But right now, there's too little content in the game to play as just one. Later.