I would argue against how it starts somewhat. It's coercian based on desperation. End of the day, we (MC) never force her to actually do anything and she always has the option to stop or not do something. A hint of blackmail perhaps (right at the start)...but nothing illegal. Maybe you actually missed tyhe fact Bella is never forced into anything. There is no abuse. Could that part of the story been slightly better written? Perhaps yes but it's a mechanic to start the route, nothing more.
I could fill 22 pages on this subject (from experience) but it has all been discussed ad-infinitum before so there really isn't any point. My biggest gripe with all this is that far too many people misunderstand what BDSM is and can be and very rarely is the loving, gentler, softer side of a dom/sub relationship ever brought up or discussed which means there are a lot pf pre-conceived notions and labels about it which for the most part, are often highly inaccurate and misguided.
(Disclaimer: Assuming all is consensual and discussing dom/sub relationships...not men who are domineering and/or the extremes of the spectrum).
I would argue back that she starts as the victim of blackmail for money, an actual crime, and that the MC replaces the blackmailer for quite a while, before coming clean and giving her the facts straight. the fact that she's not under physical coertion and can always pick the alternative (which would damage her socially, potentially cost her her job and bring harm to herself and her family) really doesn't give her much in the way of agency. Sure.. the victim of a blackmail can always refuse to pay and get his dirty pics divulged, their kidnapped loved ones disappeared or suffer any other nasty consequence for displeasing the blackmailer.. that's what makes it such an insidious crime.
She's not being told "I've got a ticket to that concert you like, if you want to come with me you have to suck me off"... she's being told "pay me money/have sex with me or I will ruin your life"... goes a bit beyond playful coercion.
I certainly do not expect even half of the game developers who plonk in some bdsm because it sells to know what it entails with any degree of accuracy.
Anyway, this is not to say that I didn't enjoy the game.. in many ways it's one of my favourites, including the dom/sub play, which so rarely has any depth at all in these games, so I'm sufficiently happy with how they handled it in this case and perfectly willing to give them a pass.