Why is prince Hamlet angry with his mother in William Shakespeare?

In William Shakespeare's play "Hamlet," the Prince of Denmark is very angry with his mother, Queen Gertrude, because marries his uncle, Claudius. He believed this is an improper marriage and disrespect for his father, the recently deceased King Hamlet. Prince Hamlet thinks his mother could be more concerned with her dignity than with marrying so soon after her husband's death. This feeling becomes one of the main reasons why Hamlet starts to doubt everything and becomes depressed.