Are you still my best friend?

How does one really face the reality that the person they're once close with, sharing almost everything like joyful laughter, tears of sadness and all possible secrets gone just like that? From texting everyday to one waiting for the other one to show effort to text first. It's been a rough couple of weeks. I am left wondering of what's wrong or what I did wrong. Is it because she is bored with me? or has she found other friends more worthy than me? Even if I've done something wrong to her, can't she come to me and just tell me about it? Aren't we best friends? When I ask her what's wrong she kept on denying that anything is. Now I am just here on standby mode so that if that day really comes, I won't fall too hard.