Some lyrics to show how the song fits:

Stranger:
You're not the person that I once knew
Are you scared to let 'em know it's you?
If they could only see you like I do
Then they would see a stranger too

You Belong With Me:
You're on the phone with your girlfriend, She's upset
She's going off about something that you said
She doesnt get your humour like I do
I'm in the room, its a typical Tuesday night
I'm listening to the kind of music she doesnt like
And she'll never know your story like I do
But she wears short skirts, I wear t-shirts
She's cheer captain and I'm on the bleachers
Dreaming bout the day when you wake up and find
That what you're lookin for has been here the whole time

Girlfriend:
Hey hey, you you, I don't like your girlfriend
No way, no way, I think you need a new one
Hey hey, you you, I could be your girlfriend

Torn Between Two Lovers:
Torn between two lovers, feeling like a fool
Loving both of you is breaking all the rules
Torn between two lovers, feeling like a fool
Loving you both is breaking all the rules

One Time:
And girl you're my one love, my one heart
My one life for sure
Let me tell you one time

Objection:
It's not her fault that she's so irresistible
But all the damage she's caused is infixable
Every twenty seconds you repeat her name
But when it comes to me you don't care
If I'm alive or dead
So objection! I don't wanna be the exception
To get a bit of your attention
I love you for free and I'm not your mother

Teardrops On My Guitar:
He says he's so in love
He's finally got it right
I wonder if he knows
He's all I think about at night
He's the reason for the teardrops on my guitar
The only thing that keeps me wishing on a wishing star
He's the song in the car I keep singing
Don't know why I do

link

The next round is where Kurt sees his hospitalized father. What song do you think would work?

and Girlfriend, hard to choose ;)