How long could she be ignoring?.Norah was continuously teasing her.She was not able to control herself.In that situation,no one can do it...they are already stressed and if their stress continues for a long time,they dont have a proper balance or control on any thing.
And if their stress level is high due to an object or a person , in that time , they/many of them just ignore it for a long time.But soon , lose control and give up.
That means they lose control and become violent ,not like the british but quite violent that sometimes they can just throw something and break it or destroy it.