Why Juliette Changed Her Mind….
I think Juliette is pregnant and was originally motivated to leave and live in the on the mainland with Sawyer and baby. After agreeing to go back and stop Jack from blowing everyone up, so then realizes that Sawyer will always love Kate and that she’s better off “never losing” Sawyer and the baby by never meeting him. She touches her stomach several times during the finale, which is an unconscious move a lot of expecting moms do….see the scene when talking with Bernard/Rose. It’s just a theory, but I think it may carry some weight!