I think this song is about a girl finding out her boyfriend is cheating on her. This is evident from the chorus and the first verse after the chorus.
"Seeing the laughter in your eyes
Seeing the smile I thought was mine
Watching you kiss her lips goodbye
Things I wish I didn't know
If I could wipe this memory,
Go back to when that girl was me,
The day that I should have stayed at home
And I wish I didn't know
I'm lying here beside you trying to block it out my mind
Just knowing that she touched you kills a little more inside, ohh
I don't wanna confront you 'cause you're only gonna lie, ooh
But what's a girl to do, just sit around and watch love die?"
She has seen her boyfriend with another girl, and it has hurt her. She knows that if she confronts him and asks him about what she saw, he will just lie and deny everything, but at the same time she wants to ask him because she needs an answer to explain what she saw.
"I've been busy denying, but my heart still needs to know"
She is saying that she has denied everything she saw, and saying it wasn't what she originally thought but now she needs to know the truth.
I think this song is about a girl finding out her boyfriend is cheating on her. This is evident from the chorus and the first verse after the chorus.
"Seeing the laughter in your eyes Seeing the smile I thought was mine Watching you kiss her lips goodbye Things I wish I didn't know If I could wipe this memory, Go back to when that girl was me, The day that I should have stayed at home And I wish I didn't know
I'm lying here beside you trying to block it out my mind Just knowing that she touched you kills a little more inside, ohh I don't wanna confront you 'cause you're only gonna lie, ooh But what's a girl to do, just sit around and watch love die?"
She has seen her boyfriend with another girl, and it has hurt her. She knows that if she confronts him and asks him about what she saw, he will just lie and deny everything, but at the same time she wants to ask him because she needs an answer to explain what she saw.
"I've been busy denying, but my heart still needs to know"
She is saying that she has denied everything she saw, and saying it wasn't what she originally thought but now she needs to know the truth.