Marie-Claire French (I think that is her name) a psychologist in Erosion of the Soul makes the point that victims of domestic abuse have two choices - to submit or to fight back.
One could add also the choice to leave, but that is not always straightforward. Carrie Symonds was in her own flat, she was asking Boris Johnson to leave. He was not doing this. She hence had two choice - to submit to what he wanted or to fight back. One might assume (I was not there) that the shouting etc was her fighting back - she had after all asked him to leave.
As soon as women fight back, it becomes seen as a high conflict relationship rather than domestic abuse, but let’s look at the power structures - powerful white male known to have a temper problem and be volatile others have backed this up; younger woman who is asking him to leave her flat. There may not have been violence but there was certainly disregard for her.
I really do not believe there is a case for arguing that CS was the aggressor here, but well done for getting in with the ‘women are abusers too’ trope likeamillpond