Nothing about this game fits into the "NTR" type game. Starting with the dev's own claims that this is not an NTR game. Steph is never meant to be stolen from the MC. The MC is never portrayed as weak, feeble-minded, small cock, impotent, or unable to please his wife. If you play this game like you would play an NTR game, you end the game. Acting like a weak or jealous dick pisses Steph off. Prior to the removal of the cuckolding path as a losing path, if you made NTR-type choices, that was the ending you got.
The intention is to play this game with bold and confident choices. Doing so gets everyone laid. Again, the original intent was that the relationship would teeter on a fulcrum; confidence got you laid, lack of confidence made you sit it out and watch, or worse, Steph got laid without you. I would buy that it would have been (or should have been) an NTR game IF the dev did not have the full intention that the player would "win" the game by choosing the high-confidence route.
That all being said, it clashes directly with the dev's statement to play as a bystander instead of as the MC. My take is that the dev was tired of answering the argument that the MC should have kicked Steph out. So, he told players to stop playing as if they were the MC; make choices for the MC based on what he would do, not what you would do.
I don't think they want to create an NTR game. I think they wanted to create an open relationship game where you got punished for not being confident. But using cuckolding as a punishment pissed off the cuckolding fans. So they changed it all so that each path was a positive take, "win-win-win," regardless of the path you choose.