There are female characters, some who are major characters, who have sex and do sexual things with characters other than the MC. If you define them as Love Interests, then I suppose you might feel jealous and call it NTR. The mother (Victoria) is not and will not be a LI, and you'll notice there's no Incest tag here. The MC's friend (Ian) seems to respect and love Victoria like a mother, but the debate, and hope for some readers, is that it might develop into something romantic or sexual, but that remains to be seen and is unlikely. So if the mother's past as a porn actress creates angst in you, like NTR might, and that's something you don't want to experience, then you probably should move on. As
Idontplay said, it's not actually NTR, but some people have expansive definitions of NTR.
dolfe67 is probably right, but it's a great game if you can convince yourself that vanilla incest harem isn't the only type of enjoyable AVN.