because jack didnt realize she was his only real friend back then
yup jack started the day saying he had no friends, and ended it saying chloe was his only friend.
Throughout it all chloe been helping jack, jack already lost everything he cared about, his wife, renee, that mexican chick, his daughter hates him, never saw his grandkids grew up, brother and father dead, best friend tony is who knows where, michelle dead, his mentors dead, but through it all chloe always been there.
the john creasy giving himself up for that little girl