Who invited you?

If this is a private party,
What are you doing in this place?
You don't have an invitation
You don't have a reservation
And you didn't come as someone's date.

So who invited you along?
And who's watching out for you tonight?
We've got security guards at all the doors,
But you've managed to get in all right.

A chill came through the room when you entered.
And all eyes were on you as you passed,
I saw smiles and smirks and "hey, how you been?"'s
And I wanted to get away fast.

I'm pulling this black tie off of my eyes
You know I know the person you've been on the side.
It is far too late--my voice gives me away,
You've seen me; there's no time to hide.

Polite goodbyes take too long to make,
Gotta thank the host before I leave,
Head out of the party and step through the door,
Before your voice calls out, "Alex, it's me."