That happens when u get older it did for me
Talk to your best friend and find ways to remain friends.
In life all good things do come to an end and nothing we can do to stop it. This may be the case here as you two may have just outgrown each other and time to try other things. You two may not stay together as BFFs but try to stay friends as none of us knows what the future holds for us so you two could possibly become BFFs again one day down the road so don't depart on harsh feelings. Things in this life just happen sometimes that have no explanation for why but just do so don't beat yourself up looking for a reason but just be prepared to move on and she will never totally leave you. Good luck
Best friends can grow apart just like cars can run out of gas.
It happens, but it's seldom inevitable.
(Unless they've left to join ISIS---which is not a typical problem with cars.)
Unless the car has been totaled, you might want to try filling the tank.
All people come in and out of our lives to
teach us something and maybe to learn then,
its time to go. We are all teachers, and students.
Just be thankful that they were a part of your life at all,
for thoughs are your real treasures.