Isn't it so easy to focus on the purely sexual between Dom and Sub? That is true in person and even on line.
So often that misses what is essential to many/most/ almost all? subs: exercising control. Us Doms do well to frequently draw back a bit rom purely sexual actions and demands so we can get back to the basics of D/s, which is some form or other of Total Power Exchange.
That is, after all, the central craving of a submissive as opposed to a vanilla. To feel the Dominant take control of her mind, setting it free to simply obey and FEEL, rather than be fretting about "doing it right" or "Am I pleasing him?"
This doesn't take a raised voice, or implied threats, or abuse. It just involves knowing what we require of our sub, and calmly, consistently making it clear.
It is what she craves.