Why hasn’t she accepted my friend request yet ?

Maybe she only wants to be connected to people that are actively in her life ? Maybe she is in a relationship and rightfully has 0 interests in having male friends due to her commitment ? Maybe she is going through a social media cleanse of toxic people online and so is not looking to be accepting friend requests right now ? Could be anything. Don't let it bother you. 

Don't no...some people r dicknobs..she will except  soon

Doesn't want to accept but can't be bothered to reject.

Here is a thought.. get off "facebook" and live a real life. Maybe she is living real life and does not have time for pretend life. 

It's simple-

She doesn't consider you to be a friend, but she wanted to be polite about your advances! She was hoping by not accepting or declining your friend request, that you would take the hint, and stop trying to contact her, without her outright rejecting you.

Leave it alone.

I get a lot of friend requests from people and I get a notification of one I think I will accept but ten when I look for it later I can't find it so it may just be lost among so many others.

Not everyone enjoyed school and a lot of people have no desire to be reminded of it. 

She does not want to accept it

She is not intersted in you

just start talking to her and let her casually come up with the decesion and if she doesnt then just dont sweat on it

Move on man. Don't get emotionally attached to a friend request. Lol. I'm sure she thinks she's better than you. Don't waste your time on such a basic b*tch.