I guess I can only speak to my own therapy--
My T has good boundaries. But that doesn't stop me from feeling like "I'd Die without him". Through my work on my own childhood neglect issues, we both came to the realization that I might have been actually in physical danger at one point, due to a caretaker's negligence. I know that I had a severe medical condition caused by neglect. Maybe the feeling of impending death has a basis in reality. Emeshment feels safer, with the right caretaker.