She hates him because he's shallow and free as a bird, laughing at everyone that got caught by the chains of routine and boredom. She pities him because he can't see that his love for money and adrenaline caught him instead, both keeping him from ever reaching satisfaction. She likes him because he's the only one in the world that tries to make her smile and forget about her past if only for a few minutes.
So as he shoots, she mutters her thanks and her apologies, because even though he freed her from the heavy chain that is her past with a single bullet, she was unable to save him from his own.