CNN:

In a political world seemingly incapable of being shocked, the resignation of United Nations Ambassador Nikki Haley on Tuesday did just that.

The most common reaction upon hearing the news, which Axios' Jonathan Swan first reported, was "WHAT????" (A senior State Department official told CNN that Haley had only told her staff about her resignation Tuesday morning. Another source familiar with the matter said Haley's resignation caught national security adviser John Bolton and Secretary of State Mike Pompeo by surprise.)
And that reaction was quickly followed by "WHY???"
 
The answer to the second question is now the big story. And, in truth, we just don't totally know yet why Haley, who seemed to be one of the few Trump administration officials able to stay in the good graces of Trump, the international community and establishment Republicans all at once, would decide to simply (and suddenly) call it quits.
 
1. She got edged out by the likes of Bolton and Pompeo

2. She needed to make some money

3. She wants to run for president

Go to link