Even though you’ve read the bible with them, prayed with them, and cried with them… people will still lie to your face.
They’ll lie about their sin, they’ll lie about their feelings towards you, they’ll lie about what they are going to do.
Don’t expect it, don’t assume it, don’t get angry about it, and don’t pre-emptively act on it, but at the same time, don’t be surprised.
Be sad, mourn sin, but know the extent of the fallen world we live in enough that you’re not shocked by it.