In act II of Hamlet what does the queen believe caused Hamlet to go insane?

Answer 1

"His father's death, and our o'erhasty marriage." She thinks it's a combination of grief over his father, and anger and confusion over the fact that his uncle is now his father, and is king instead of him. She's not far wrong.

Answer 2

Hamlet's madness was likely associated with the death of his father. He felt a mixture of sadness and anger due to Claudius and Gertrude's actions. Towards the end of Act 3, Hamlet reveals that part of his madness was faked, as it was "in craft".

Answer 3

"I doubt it is no other but the main: his father's death and our o'erhasty marriage." Shrewd guess, Gertrude. She doesn't know about the ghost and the fact that her first husband was murdered by her second though.

Answer 4

Of course, it is an endless debate whether or not Hamlet is actually mad or whether he is "putting an antic disposition on." There are times when he does appear a little unhinged, especially right after he has spoken with the ghost or right after he has accidentally killed his girlfriend's father. These are events which might unnerve anyone, and small wonder if he temporarily loses it. On the whole, though, his behaviour is more consistent with an assumed eccentricity designed to focus Claudius's attention away from the fact that Hamlet intends to kill him, and to explain any peculiarities of behaviour as Hamlet works toward that ultimate end.