I just lost the dearest person to me why do i feel it was my fault?

I just recently lost my dearest friend Summer she was so innocent never drunk never smoked never hurt anyone And god felt it was necessary to take her away she was only 21, im only 19 and never got to tell her how much i loved her, she was hit by a car on the same track ive ran on for 4 years i got to the finish line and she never came why do i feel its my fault why do i want to kill myself to make amens for her death .. she was so beautiful ill never be able to forgive myself