To be fair, what they are asking for isn't wrong. There have been other NTS where the wife/girlfriend do enjoy their time with the partner they are with, but come back to the husband/boyfriend/significant other plenty of times. The thought of having them be stolen away does get some people off in a way.
An example, in my opinion, would be something like Tsubame-chan from Terasu MC. There are multiple occasions where she says the Bull was excellent in the ways of Sex and would do the recording in such a way that got her Boyfriend off, but in the end she always comes back to the Boyfriend.
Another is Yumi/Yura from NT00. Yumi/Yura does the NTS for Haru as something that she knows he likes/loves. The thing is that she does it well enough to say that she enjoys it, but really doesn't fall for Jin. It's all for Haru.
Or from Nyatorase, with how Kat gets lost in the Sex that she sometimes forgets the MC, but is always coming back to loving him.
This is more of trying to see all sides of NTS. Maybe more Hard NTS is what they are looking for like the examples above?