She wasn't equipped to defend herself from being indoctrinated and radicalised.
How did she come into contact with that indoctrination and radicalisation, other than through conscious, sustained choice? How many fifteen year olds are able to steal the price of a plane ticket it, obtain a passport, buy the ticket and catch the flight? That's not like getting into the car of a man you met at the chip shop, being plied with drink and alcohol, being sexually assaulted and then blackmailed into continued co-operation with abuse. Where's the threat? Where's the grooming? This was a choice.
We were repeatedly told that their families knew nothing of radicalisation which was (a) extraordinary if true, as you would have thought Muslim parents would be aware of the risks and (b) as it happens, in at least one case a bare-faced lie, as at least one sets of parents were straightforward extremists who were if not members at least enthusiastic and active supporters of a banned terrorist organisation. We were also told how clever they were, Astar pupils, and so on.
In Rotherham and Rochdale, the victims of grooming were mostly marginalised children already known to, or who should have been known to, social services. Although their parents may not have crossed the line into actionable inadequacy, they were not strict, deeply engaged parents: your 13 year old being routinely exposed to the "night economy" is not a mark of engaged parenting. They were struggling in school, truanting, otherwise disengaged. Children's services are rightly lambasted for not picking up and dealing with these signs.
So far as we were told at the time these children disappeared from Bethnal Green, none of that was true: these were bright children from supportive households, successful at school, plenty of friends, no social services involvement. Model families, in fact. So what happened?