I think most women feel threatened by it. Face it, if she catches you watching a scene where the slender, large breasted, constantly gagging for it blonde has a well hung male star slamming in her ass at will only to dump a load on her face, shes going to thing thats what you want and will expect from her. Of course if thats something she is uncomfortable with or outright doesnt like, then her refusal to catre to these fantasies might place in her mind the danger that unless you get it, then you'll leave.
Then the flipside if she does decide to indulge at the expense of her own feelings and self respect, then it opens a pandoras box of its own, can she stay with you, do these things for you and bring herself to accept this is what it takes to keep you?