Beckett is Devastated - Season 1
In the Castle season 1 finale, "A Death in the Family" Kate Beckett is devastated when Castle does the one thing she asked him not to do, look into her mother's murder.

Castle Quotes

Sometimes the hardest things in life are the things most worth doing.

Castle

Castle: How do you know when you're in love?
Beckett: All the songs make sense.