Second book in the Dark Romance series, The Jewelry Box...

"I made a bargain with a monster.
A vow to save both our lives.
I thought our commitment would stay true.
It didn't."

I've spent my entire life alone.
I'm well used to loneliness and the endless pain of having no one.
Sure, we made a bargain. We shared our secrets and made a vow.
But I warned her not to do one tiny thing.
One very important thing.
For a while, she obeyed me.
Until the night she didn't.
And now...the connection we shared?
That alliance we forged?
It's broken.
I'm broken.
And by the time I'm done with her...she'll be broken too.