So, let's go ahead and stake out some intellectual territory and see if I can defend it.
The relationship of the Andor family to be B2EMO is probably the most abusive we've seen the relationship be outside of Jabba the Hutt's palace and is maybe more dysfunctional than the way Jawa's treat droids.
Fundamentally the reason for that is we've never seen a less happy droid. B2EMO is the most insecure and emotionally pained droid we've ever encountered. Every time we see him he's uncomfortable and needs comfort. And fundamentally, that's because he's being abused in multiple ways. Canonically - and yes I'm aware this makes no sense - B2EMO is supposed to be a salvage assistance droid. Let's let aside that it's obvious that out of universe B2EMO was designed not as a rational salvage assistance droid, but to be emotionally evocative on screen. Let's pretend he is a well-designed salvage assistance droid even though it's obvious he's not. He's more of a panda/puppy designed to be cute.
B2EMO has been abused in multiple ways. First, B2EMO was initially forced to cooperate in illegal salvage operations, something that almost certainly caused him emotional distress since behaving immorally would have been against not only a general emotional framework for friendly droids, but would have been specifically against the emotional framework you'd want to give a salvage droid - don't take and cut up stuff that doesn't belong to you is something a salvage droid needs to understand to be functional salvage droid. It's possible that B2EMO was professionally programmed to accommodate his new operating framework, but I don't think so. I don't think the illegal operation was profitable enough for that. So I think Keef and Maarva did their own programming, most likely through crude verbal commands, to get B2EMO to go along with this, but it clearly makes him uncomfortable to be in a criminal minded family but not have the emotional framework to accommodate that. Quite rightly for a simple benevolent droid, he doesn't want to lie or steal or otherwise do the wrong thing. But here he is.
After Keef and Maarva left the illegal salvage business, they lacked money for B2EMO's upkeep which led over time to B2EMO's physical body deterioration - something that clearly causes him pain and emotional distress. Quite obviously, one of the moral preconditions of owning a droid is being responsible for the droid's upkeep. They are trusting their owner to repair them and to treat them according to the owner's manual. But lacking the wherewithal to do so, they don't sell B2EMO, but instead keep him in increasingly uncomfortable (for him) service.
Moreover, they repurpose B2EMO. Instead of using him according to his primary function as a working companion of a laborer in a salvage yard, Cassian makes him a surrogate companion for his mother since he himself is not a very attentive son and also can't afford a new droid that could actually cope with this demand. B2EMO the salvage droid becomes B2EMO the companion droid and B2EMO the domestic helper and errand runner, things that a salvage droid just would be ill-equipped to do. Nonetheless, trying to be a loyal droid, B2EMO soldiers on trying to do his best to fulfill jobs he's not really capable of and which he wasn't programmed to find emotionally and intellectually fulfilling. And he's mostly miserable the whole time. And, he can't just memory wipe and do a factory reset even though his emotional framework is telling him he's going increasingly insane, because he has to retain all this information about being a domestic helper and emotional support companion he wasn't programmed with. He knows that Maarva needs him as surrogate emotional support because Cassian is never around, so on he goes with all his insecurities, worries, and pain.
And we see the result - a droid in some of the worst emotional pain we've ever seen a droid in. A purpose built companion droid would have built in the understanding and emotional framework to deal with the loss of their owner. You would have never seen such a droid be in pain like that because why would you build a droid that way? No, you'd build it to know it needed to support the humans around it in their time of loss and to be emotionally fulfilled by that and to count that as 'grieving in its own way'. Why would you program a droid to suffer just because a human would? That would be unethical and immoral and probably get your license to make AI revoked in any civilized universe.
Probably in his natural state B2EMO would be completely pain free right now, since the death was not the result of an error on his part on the salvage yard - concepts he'd understand. He'd be just like, "Ok, who needs me now? I want to work." But having been ad hoc programmed for so long and having been used so far outside his intended purpose, he has no way of knowing whether Maarva's death is the result of his failure as a companion, no way to understand what happens next, and no way to access a blissful factory reset to restore his happiness.
And into this comes one of my favorite characters on the show, the well-meaning and good hearted Brasso and he tries to comfort B2EMO like B2EMO is a human, with clearly absolutely no understanding of what is going on in B2EMO's head. For example, he asks a droid that is programmed to work alongside a human, and who has been forced to be an emotional support companion (essentially a pet) for his owner for a decade if "he wants to be alone". And B2EMO is of course going, "No!" Brasso of course eventually does do the right thing for the droids emotional well-being, because he's a good guy, but still.
B2EMO has been unintentionally abused nearly as severely as Dobby, Winky, or Kreacher. One hopes Cassian grows morally enough to rectify this situation. Or if not, let's hope Brasso actually uses the droid as a salvage yard companion, repairs the droid, and starts undoing the damage.
