playing for the first time and great game so far but
first time ive been really confused by the story.
I'll add in that Julie has a small child and the place she is at offers more protection than leaving with the group.
IMO - she and Sydney were kicking the can down the road - needing to make a real decision about leaving versus 'hoping' that this would be a safe enclave against the bandits and zombies.
(Sydney's hopes for meeting family as mentioned above also strongly influence her decision to stay. Keep playing and you will see how those decisions and the reasons for them could change for one or both women - depending on your earlier choices.)
Cheers!!