Whatever you might call it, it's not cucking and that's the whole point. People who bring cuckolding and netorare as terms in the discussion are simply flat out wrong.
Is the player passive in that scenario? He is, but that's a complaint about player agency and the game having a linear story instead of a branching story. It's a whole different matter. The game has a story and since it's linear you can't fine tune it to your tastes. But that doesn't mean you get cucked by Grug. Besides you concede it's not cuckolding then talk about Ziva being the MC's sexual partner: she is not! She has never been, she has only, up to that point, had sexual interactions with him in exchange of something else. She's used you to break her curse and then asked for money for every act. That's a whore for you, not a sexual partner.
And it doesn't matter that the MC is willing to fight and risk his life for her. That doesn't change the fact that she is a whore and has never established an exclusive romantic relationship with the MC.
The fact that she is reluctant in that instance to give in to Grug's request doesn't change the situation either.
Facts are facts regardless of how people involved feel about them.
At no point the MC and Ziva have been a couple before that scene, thus there is no NTR, cuckolding or the likes, the terms are completely misused in that instance.
