Thanks, very convincing analysis and presentation of the boss's modus operandi. Especially this switching from one mode to the other, this is undeniable, and therefore this shows again and more precisely his malicious intention and aim at controlling and manipulating the couple.
For me the essential point about "abuse" is that I think to be a meaninful concept it has to mean that the target/victim operates under a limited capacity of free will/self-defense. (and therefore Stockholm Syndrome is important, don't want to go into too much detail here, I refered to the classicl definitions 70s and early 80s (the perpetrator is seen as a sort of rescuer from life threatening situations he himself has caused, as the only one on whom the vicitm's life depends), from the mid 80s they somehow merged it together wit Battered Wife Syndrome and extended it, that's right. That's important here in our context, because the sense of their life being in danger was implied also there: the Syndrome was the defense basis in trials against women who preemptively killed abusive husbands in self-defense. So it has this implication of at least the perception of a very restricted freedom and of immediate danger. And it has always to include physical violence, together with psychological)
If we follow this idea, that the boss's manipulation works this way against Vivian (and Hutch as you seem to hint at) this has I think important consequences for the interpretation and the plot of the VN. Vivian would right now already (since when precisely?) be in an abusive relationship in which she doesn't completely control her actions anymore. She would then really be a victim in the proper sense. You couldn't for example see her as a "whore". I myself would at the moment like to think that she still has the capacity to freely walk away from every situation. She just had a few encounters with the boss up to now, she is not an unexperienced teenager, she has Hutch (isolation is an important factor with Battered Wife Syndrome) if she wants. I see the shock element in the car-situation that you show very well, but after that she can distance herself again. It would be different if the boss would insist on her staying with him for example.