Jealousy

Why people are inborn with the feeling of jealousy?
Does it plays any important role in our daily life?
Is there any contribution done by jealousy?

How I wish that I don't have the feeling of jealousy.
This feeling is driving me crazy.
I tried to control but I just hardly manage to brought it down.
The flame of jealousy just keep on eagerly fired up.
I felt like I'm the stupidiest person on Earth.
I don't know why I'll ever fall for a girl like her.

Now, I can understand why her boyfriend felt so insecure.
I starting to know that kind of feeling.
Whenever I saw her and other guys having some intimations,
my eyes are burning with the fire of jealousy.
And what was aching my heart even more is she likes to talk the good of other guys.
Not that I want to restrict her for her own rights, but its made me felt like I'm worthless.
Anyway, I've been doing my best to help her in anyway that I possibly could.
I'll just wish for a betterment after this.