In his soliloquy, what are Hamlet’s reasons for objecting to his mother’s remarriage?

Answer 1

To deal with his soliloquy in I ii in order: much of what upsets Hamlet is the ease with which she has forgotten his father :

That it should come to this!
But two months dead: nay, not so much, not two:
So excellent a king; that was, to this,
Hyperion to a satyr; so loving to my mother
That he might not beteem the winds of heaven
Visit her face too roughly. Heaven and earth!
Must I remember? why, she would hang on him,
As if increase of appetite had grown
By what it fed on: and yet, within a month--
Let me not think on't--Frailty, thy name is woman!--
A little month, or ere those shoes were old
With which she follow'd my poor father's body,
Like Niobe, all tears:--why she, even she--

Hamlet then swings back to the metaphorical again, comparing his mother to “a beast that wants discourse of reason” and then he moves to express the problem literally:

married with my uncle,
My father's brother,

Hamlet attacks his mother for marrying her dead husband’s brother, because he is not as great as the late King Hamlet. Taken together, his comments on his mother and his father seem to imply that Hamlet feels as if his mother never really understood the greatness of his father, either that or it was a great failing of hers to devalue his father’s memory by marrying incestuously and hastily.

I would recommend http://www.shakespearehomework.com/homepageHS.htm which has explanations of all of Hamlet's soliloquies, in greater depth. This is an excerpt and was taken from the page
http://www.shakespearehomework.com/page23.htm

Answer 2

The speed with which she hooks up with his uncle, the fact that it's his uncle, who is totally lame compared to his late father, and her absolute weakness of character.

Answer 3

you don't even need to read hamlet to guess some answers to that one! what would any son's reasons be?? especially a son whose stepfather is now the leader of a country thanks to marriage to his mom?? think it out.

Answer 4

Cause she wanted to marry his brother.