I heart you, you haunt me (Simon Pulse 2008) and Far from You (Simon Pulse 2009) by Lisa Schroeder both deal with the grief caused by death.
In the first book, I heart you, you haunt me, Ava's boyfriend has died and we see what she's thinking in short tight verse. One moving example:
could bring him back,
there'd be enough
to bring him back
a hundred times."
But then Ava starts hearing and seeing Jackson. Is she going crazy or is he a ghost? If he's a ghost, why is he haunting her?
In Lisa's second book, Far from You, Alice's grief is much older than Ava's, but still Alice has not let it go. She's resentful of her stepmother and her newborn half-sister (emphasis on half!). She and her best friend have had a disagreement and aren't really talking. Alice's dad makes her go on a trip with the three of them and a snowstorm changes her life.