Why can't my 'best friend' decide one way or another?

Well obviously she isnt ready for dating anyone. She said it herself she is confused and to busy. She may be interested but let her get her mind right first. In the mean time u can enjoy other girls and/or continue to be there for her. Give it time when she is ready she will let you know and if u still want to then get with her but if ur in a relationship u decide which girl is better for you.