In communication what is the. meaning of groupthink

Groupthink means an occurrence where by a group comes to a unanimous decision about a possible action despite the existence of fact that points to another correct course of action. 

it ends with a marriage, but also with prospero giving up his power.

the tempest is a play written by william shakespeare between 1610-1611, it narrates the story of prospero a magician that sets a storm to wreck a ship, this sets the story to kill the king of naples. while it is a romantic style play, it isn´t traditional because of the ending, it end with the marriage and the magician giving up his powers.