Hard to Love

I told myself I'd never allow this to happen. All I wanted was some fun.
I never expected that meeting her would turn my life upside down.
I want her more than anything, even though I shouldn't.
Now, there's more to lose than just my heart.
She doesn't know, she's my best friend's little sister.
My fate was sealed a long time ago. Loving her was never in the plan.
But plans are like promises, they're made to be broken.
I just hope, I don't break her in the process.