ZD:
You are correct, that the behavior we observe could be just cooling periods, much as climate varies due to factors that we can’t identify. But the overwhelming majority of cases involve a form of rebellion. The kids are purposely and consciously rejecting the “frum lifestyle”. There are reasons for this, but it is enticing to blame everything on the family, the school, the internet, spoiled kids, etc. There may be common factors to many situations, but it is often difficult to know which observations are causes and which are effects.
Having quite a bit of connection to the “parsha”, I do have a label for what I believe is universal in ALL cases. REJECTION. Now it is incumbent on those involved to determine what, where, how, and when. The refu’ah is to swing the opposite direction, with the wealth of love, unconditional at that. That’s all that works, and so say the Gedolei Hador.