why?

okay, let's play a game. i'll tell you a story and you need to answer all the questions.

i have a best friend. let's call him/her A. i knew A for 5 years if i'm not mistaken. i'll always go to any event with A. we had so much fun in all events i guess. or maybe i'm the only one who had fun if A is just faking it. sometimes we fought over small things. but then we will forget about it and start anew. A is a good supporter. A will support me in anything that i do and this give me courage to succeed. whenever i had problem, i'll tell A and A will always be a good listener. i know that A didn't know how to solve all the problem i had but he knew how to make me calm. but things change so sudden. out of nowhere, A is avoiding me. A also block me on facebook. i call A for few times asking if A is mad at me? A will answer, no i wasn't. but A admit that A is avoiding me by not replying my text and not answering my calls because A wants me to move on.

so the questions are:

1. why A did this to me?
2. what i should do?

- please give me an advice to help me going through this