Oh dear, David.....our older parents can be frustrating at times, and I do sympathise.
It gets that way, sometimes, that we are like the parent to them, and can recognise a dangerous situation and even forsee the consequences of their actions....and so end up being the ogre by trying to stop them being hurt.
A break will do you good, and it looks like you have plenty to eat...lol
You seem to be doing a great job of looking after your Dad. They can be stubborn, but they know you care.