None of them were actually brainwashed. The love potions only made them 'like' Pina and amplifies that feeling (e.g. in the previous chapter Angel asks if they noticed that their fondness towards Pina was gone after they drank the special wine). The prince was always an egotistical bastard who...
An FL with a moral backbone and the wits to play political games is so much more fun to read about. It makes it more believable that she's able to draw the princess's harem away from her because of actual charisma rather than forced cliches.