I really like the style you are going for the game, looks really good.
A couple questions, what kind of NTR you plan to add? When you add it, will it be optional?
Some towns will be able to get corrupted, causing scenes with civilians and those of another race/town.
You'll be able to see some NPC's lives get destroyed as a goblin fucks their wife behind their back for example.
As for members in your group, I was going for something a bit Roundscape Adorevia-Esque where your group can basically have sex scenes together or with other people, which some people view as cheating/NTR I suppose even though you're not technically in a relationship.
As for getting NTR'd, I plan on adding a warning whenever you can recruit a new member to your group along the lines of "Warning: This character creates an high amount of NTR content", together with their unique possibilities. E.g. "Impregnation, Romance" so you can decide yes or no.. although I'd also like to introduce NTR when you're basically neglecting one of your groupmembers for example, causing them to be unhappy with you, regardless of the character.
However, I only think of NTR when we're talking about a few characters you can truly "romance". I'll introduce a few of those, some of which will stay in their towns. Romance characters will only have sex with you; unless they have the NTR warning or unless you're neglecting them / doing things to make them unhappy.
Hope that answers your question.