This song is about a girl, but she is only pretty because she is forced to be.

on the outside, it appears that she has it all together, the perfect, happy life, but inside this life is killing her because she is so unhappy with the person that she must pretend to be.

now she feels isolated and alone : she has no one who truly knows who she is, no one can penetrate this facade that she's created and hid behind for so long.

so after working so hard to be something she's not, to live up to everyone elses ideals, now it seems that all she can do is let people down. She no longer has the energy to please everyone else and it is making her empty inside because for so long, her life has only been about pleasing others. That was the thing that filled her hollow shell and made her real. now she knows that it was all fake.