Guilt. It is like a self imposed prison that can take many forms, such as resentment for the often difficult, never ending drudgery of listening to someone with advanced dementia repeat the same question fifty times an hour, and snapping at them for doing so. Simultaneously you feel like getting in the car and driving off, (never to return!) and then you are deeply sorry for losing your temper, for you completely understand your loved one has no control over this very normal behavior (for those with advanced dementia).
How could it not drain you? Unless you are not human.
There are so many ways to cope with repetitive behaviors. Call and schedule an appointment if you would like to acquire some skills in this area.