This.
It's something that I think is common to her personality and her beauty queen role / facade. She identifies so closely with the role, I don't know if the two can be separated.
For some reason (I thought beauty competitions died out in the 80s) she believes in every cell of her body, that she has to retain poise, decency, and avoid controversy. I am inclined to think that this is a straight jacket that suffocated a different personality.
I'm not saying that she's "fake" and ought to behave differently. I hate that nonsense word and accusation. But I find her steadfast adherence to this desire to be proper, just about to the exclusion of other personality traits, quite unusual and interesting.