Dad is a WWII vet and very strong willed, Mom has dementia very bad. Dad's health is horrible, he can't hear at all and can only see a short distance. He thinks he can take care of Mom but he can't take care of himself. He has to have help to take a bath and go to the bathroom. They are not eating right.
A third party (non-family member) can sometimes help with these issues because that removes the family dynamic and the feeling that the "kids" are trying to boss them around. Do they have a rabbi or pastor who could talk with your dad?
Or a good friend of their generation who can address his worries? Do they know anyone in assisted living or a good nursing home who could tell them it's not so bad?
Sometimes all people can do is wait for an emergency and then move them - with the aid of Social Services, if necessary. I hope it doesn't get that bad for you.
Please keep checking for answers here, because many in the Agingcare community have had similar issues and they will be able to commiserate with you, and hopefully provide some insightful answers.
Good luck!
Carol