I Thought You Were Mine

I sit in the shadows
Watching, hoping I wasn't right
But then I see you both
I try to hide my emotions
As I watch you kiss her
Why would you do something like this?
I thought you were mine
You walk her to her door
And whisper something in her ear
I'm fighting the tears now
When her door closes
I come out of my hiding place
"How could you treat me like this?
I thought you loved me
I thought you were mine"
I turn and run
Knowing that you will be gone tomorrow