I think she is the abuser, the one who is violent during sex.
Her fear of violence is an act, the knot and the way she held the tied Yuuna was suspicious and the shaking at the end is not fear but excitement.
I like how this was done, in delinquent manga this situation would normally be solved by throwing hands, which I would not doubt it will eventually if this arc is still going, but it is new to see the villain actually getting away with it and it fits the overall theme of growing up this arc has.
Miyabi is literally jeopardizing his plans just for the lulz.
Before the last two chapters, does anyone have the demons' height chart?
https://mangadex.org/chapter/765122/24
Apparently it's from the series handbook