Help in song interpretation

What is your interpretation of this song? I get the jist of it and then some but…. some lyrics seem really deep or am I reading to much into it?

a reply to: KrustyKrab

If I were to propose a video:

She's at a party in a fancy penthouse type setting.
Laughing along with some stupid joke.

She's slightly tipsy,
she turns and heads for the bathroom
her smile leaves her face.

In the bathroom, she sings that song to the mirror
(her and her image facing each other)
while not looking very happy.

Toward the end of the song
the mirror image changes to a younger version of herself
not looking back at her, but rather looking out unfocused
with a hopeful type expression.