I think tempering expectations is helpful. Dementia means there is brain damage, so behaving appropriately, being cooperative, appreciative, etc. is not a given. My dad may tolerate a family gathering for a short time, but then goes to another room. It’s too much for him. He’s not being rude. It’s brain damage. I would not expect an adult conversation with my dad, though he does ok at times. For me, it’s helpful to remember it’s a medical issue, not a diss against me.