Some of the dumps might be straight caregiver burnout. It does happen and it's pretty brutal when it does. When my mom went downhill her entire personality changed and she got really mean, it was horrible. I honestly wanted nothing to do with her by the time she finally landed in the home in crisis, I lost my 20s to caregiving. I do visit her at least once a week still, and I'm much happier with her relationship now that the responsibility is off my shoulders...but coming out the other end of that hell I do understand how people can just be done. I agree with you, but when I read your story, I do not see a "dump". I see a daughter who did the best she could for her mother and made changes to the plan as her mother's needs changed. Very different from the people I have heard say "Put Mom in an inexpensive nursing home. We want something left when she's gone". And yes, I have heard the "children" who were supposed to take care of Mom in her old age say this. Sorry, but that's a dump. A person realizing that their elderly parent needs more care than they can handle and who places their elderly parent in an appropriate facility is not "dumping" anyone anywhere.
This is why having kids to look after you in old age is such a selfish pile of crap. I would NEVER wish on my kids what my mother put me through. Idealy they won't be having to do that, when I see them when I'm old I want it to be for a visit...not them driving me to errands, or cleaning up my bodily fluids, or investigating a halucination, or cleaning my home while they still have their own responsibilities. They are my children, not my future slaves. It's my job to plan for my eventual decline in abilities and that doesn't mean assuming my kids will pick up the slack. It means ensuring that I have the money to go into assisting living when I'm no longer able to take care of me and my home.