Respuesta :
Queen Gertrude wishes that the reason of her son's obvious insanity may be his love for Ophelia. In Act 3, Scene 1, she says: And for your part, Ophelia, I do wish That your good beauties be the happy cause Of Hamlet's wildness. So shall I hope your virtues Will bring him to his wonted way again,To both your honors.However, in Act 2, Scene 2, when Polonius tells Claudius and Gertrude, "...I have found / the very cause of Hamlet's lunacy," Gertrude says to her Poloniys: I doubt it is no other but the main,His father's death, and our o'erhasty marriage. From this, we can understand that Polonius' explanation of his diagnosis of Hamlet's insanity as being the result of his foiled passion for Ophelia has some influence on Gertrude's thinking. When Claudius asks her, "Do you think 'tis this?" she replies, "It may be, very like." So the Queen would like to think that she is not the cause for her son's apparent madness, although she may still secretly fear that she is at least partially responsible.
I believe the answer is: the death Of his Father
The death of the King (his Father) caused Hamlet a lot of Grief, to the point where he was filled with suicidal thought.
On top of that, his mother made matter worse by marrying his uncle not long after the death of his father.