NTR is "his passion"?
Have you actually played this game?
Because not only is NTR in this game minimal, it's also entirely avoidable. If NTR was Will's "passion", the game would be full of it and it would be the central focus, but it isn't.
I honestly don't know how you could have come to that conclusion.
I think that's a fair answer. As his "landlady", you'd naturally expect that a sexual relationship with him is going to take some time for her to be comfortable with given the nature of their relationship, but with his actions leading to her becoming more and more sexually frustated and without getting her to focus those frustrations on himself, she's going to look for satisfaction elsewhere and be somewhat more willing because there isn't that same taboo as there would be with her "tenant".
Who's to say she won't be a "slutty, whorish, nympho" when she finally goes the distance with the MC? What Will was saying, and they're quite right, is that she does this with others because the MC is building up her sexual desires but also letting them run wild rather than keeping her focus on him and thus making her desire only him. Therefore, in making her desire only him, and once they finally cross that threshold, that same cock-hungry desire she has with others will be focused solely on the MC because he has made himself the only man she desires. So that side of her will come out when she's with him and could then even start to be directed towards the other "tenants" living with her since that barrier will have been broken.