"As Your Former Friend"

Now I see what drove us apart,
Something besides that wall:
You grew up, and I did not;
I stayed obsessed,
And you moved on.
And it makes you a better person,
But it makes you less fun.
So all I can say is,
So much for your little rival,
Your little obsession,
So much
For what turned into...
I have no idea what.
Suddenly everything is normal,
And as your former friend,
I'll tell you it sucks.