I've not read the books or seen this episode yet, but isn't this true of all charismatic rulers (or dictators.) When they take power it is on a wave of goodwill and patriotic ferver. It doesn't take much time for them to put a few steps wrong, and to take their eyes off the ball, for that to change. Same is true of politicians - look at the steep rise and falls of the popularity of Thatcher and Blair. I expect the Mad King was once loved.Her journey is also getting a formulaic. I make this the fourth city-state she's about to conquer. She needs to do something different.
At least she has Dragons!