Usage of 'between' & 'among'

As per my understanding 'between' should be used when talking about 2 things/items/groups etc . and 'among' should be used when talking about more than 2 things/groups/items

Quoting gmatclub grammer book here:

The word between is always used when talking about a distinct relationship of two individual items, groups, or people.
Examples:
Sally had to choose between the red and white dresses.
Let’s keep this secret between you and me.
However, between can also be used when talking about a distinct relationship of more than two individual items, groups, or people
Examples:
Johnny had to decide between going to Europe, buying a new car, or staying in college.
Business negotiations between the governments of the United States, China and South America are going well despite cultural differences.

Can someone please explain why the examples above ( in bold ) are correct ? shouldnt among be used here ?