Who was on the throne before George VI? Why he stopped being king and passed the throne to George VI?

Answer 1

Edward VIII. Edward abdicated the throne because of his affair with Wallis Simpson, an American woman who was still married at the time, and Edward's position as Supreme Governor of the Church of England prohibited marriage after divorce.

Answer 2

George VI succeeded the throne unexpectedly after the abdication of his brother, King Edward VIII.

On November 16, 1936, Edward met with Prime Minister Stanley Baldwin at Fort Belvedere and expressed his desire to marry Wallis Simpson when she became free to do so. The Prime Minister responded by presenting the King with three choices: he could give up the idea of marriage; marry Wallis against his ministers' wishes; or abdicate. Edward duly signed an instrument of abdication at Fort Belvedere on December 10, 1936 in the presence of his three brothers, The Duke of York, The Duke of Gloucester and The Duke of Kent. The next day, he performed his last act as King when he gave royal assent to His Majesty's Declaration of Abdication Act 1936 which applied to the United Kingdom and all the dominions except the Irish Free State. The Free State passed the equivalent External Relations Act, which included the abdication in its schedule, the next day.

Answer 3

Edward VIII - the brother of George VI
Edward wanted to marry a divorced woman and even worse she was american.
If she had been german (as was traditional in the "british" royal family) he might just have got away with it.
But the situation was unacceptable to the Church of England and the government so he abdicated the throne and his brother had to become king.