How did King George's feelings toward the colonies change after the Boston Tea Party?
He went from being annoyed to being extremely angry.
The "Tea Party" happened in 1770. The Americans threw about $1 million dollars worth of tea into the harbor over the tax placed on the tea. They (Samuel Adams in particular) wanted to send the message "taxation without representation is intolerable."
King George was not particularly happy with his Massachusetts colony prior to the dumping of the tea, but afterward his anger was almost unbridled.
In retribution King George ordered all governors be replaced by English Governor Generals. He also ordered the court system, particularly the maritime courts, be presided over by English judges. And although these acts were meant to apply to all 13 colonies, nowhere were they more obvious than Massachusetts which the King considered the root of all disharmony. He was probably right on that point.