I am scared of a relationship?

I really like this girl in my school. Her looks from her red hair, beautiful eyes, good looking body, smiley, and her personality of her is awesome, she actually talks to me, she is nice and sweet, we communicate pretty well. I want to go out with her so bad, I am not saying that I can though because every time I say I can get this certain girl, it never ever works out. But, anyways I really wanna go out with her, but I am scared of a relationship. I don't know why, every time I think about being in an actual relationship it makes my head foggy and I feel uncomfortable about it. Why is this?