Result line of model and help converting to a positive intentional model

I am struggling with the result line in many of the models that I am doing on relationships in which I am challenged. It is easy for me to fill in the result line for a model relating to my weight and overeating, which would be to gain weight. However, in many of the relationship models I often end up with a feeling as my result – typically feeling guilty for feeling those thoughts and my associated behavior, and frustrated because the behavior of the person doesn’t change.

Here is an example of an unintentional model and some background. My dad is 80, has pretty strong anxiety. He has had it his whole life and has times when medication helps but also times when it doesn’t. He is also experiencing some cognitive decline and has to take several different meds for his health conditions, one of which he is in a fair amount of pain. There are two medicines that could help but he won’t take them because he is afraid of taking too many medicines. We have already confirmed that those meds won’t have a negative interaction with his existing meds but he still is nervous. He may try it for one day but then stops because it may have a small negative side effect. My parents are pretty isolated due to Covid 19 and also don’t have a lot of friends, partly due to my dad’s anxiety, so I tend to be their lifeline from a distance (we live 5 hours apart). It is what they think and partly what I think because I want them to feel better. Incidentally, that is part of the problem. I want my Dad to take the medicine so I can feel better.
C- My dad won’t take new medicines
T – He is driving me crazy when he won’t take his additional medicines to try to feel better
F – frustrated
A – am very direct and what I think is a little mean when I talk on the phone with dad what he should do to help him. ( I think I am actually more fuming inside than being mean but I am being very direct)
R – I feel guilty (this is a feeling). I know is always supposed to prove the thought, but does it here?

When trying to do the intentional model, I am struggling. If I change my thought to be more empathetic, I still have frustration in the end because he still doesn’t feel better. I know he is an adult and I can’t make him do something he doesn’t want to do but he is my dad and my parents need my support. My parents call every day and say Dad is struggling
and in pain. If I made a boundary, I don’t think this would be good because they are isolated and tell me all the time how much I mean to them and grow it helps to be able to talk to me.

Thanks for insight you can give me.