BFFs: Why Is It So Hard For Girlfriends to Get Along?

Imagine two homegirls both get cast in a meteoric TV sitcom that will change television as you know: Now multiply that by 100.
That is what Tichina Arnold and BFF Tisha Campbell-Martin experienced in the early 1990s as part of the cast of "Martin," comedian Martin Lawrence's kick-door into television.
The friendship that they had on show translated to real life.
They really were and are friends.
And that's a rarity today, because so many women have said the following sentiment: "I don't have alot of girlfriends. They're too messy" or "too jealous," or my favorite, "just too much drama."
Mind you, we're not talking teenagers here, which means that as an adult your chances of even meeting new people let alone friends diminishes gradually as you become attached to a certain routine of life.
I guess the question is:
Do sisters be hating like that?
Why?