There is an extreme lack of separation of the child’s identity and motives from those of the primary caretaker, and extreme dependence on that person’s approval, due to being regarded by the caretaker as a means to their own neurotic goals, not regarded as an independently real person.
An enmeshment is an extreme entanglement/lack of differentiation of values, psycho-emotional conditions, motives, and goals – indeed, of sense of ‘being’ distinctly different people – between what would, in health, be two separate units: the parent and the child. One could say that the umbilical cord hasn’t been cut on either side, though the parent was supposed to initiate that.
This enmeshment develops – the parent didn’t cut the psychological umbilical cord – because the child is not a ‘real person’ to the parent, merely a pawn in their own subconscious emotional need-games, merely a means or a hindrance (!) to their own neurotically-driven goals/motives/ends.
Over the course of childhood, the enmeshment/lack of separation gets ‘installed’ in both persons and becomes their ‘dance of life’ together. (With respect to the child, , see Black Hole) For the caretaker, the enmeshed child exists only as a sort of extension of themselves, not as a ‘real’ and ‘distinct’ autonomous human being whose own nature and needs should be taken into account, respected, and supported. (The latter attitude would enable the development of a Natural Sense of Self.)
For the child, the caretaker exists not as a ‘living person with their own needs and wants’ either, but only as a means to the end of getting the positive reflection back (approval) that it so desperately needs to fill its inner Black Hole‘ with ‘feel-good-about-self.’ That state enables the child to feel some fleeting, superficial version of ‘I exist, I am real.’ In this theory, this kind of relationship is called ‘Enmeshment.’
The existence of an enmeshment indicates that the child’s very sense of existing as a person, as a being, is developing in a stunted, distorted, neurotic, suffering-inducing kind of way which becomes dependent on what the other part of the enmeshment (the primary caretaker) thinks or feels about him or her, about her or his behavior, at any given time.
What the child has learned doesn’t change when it grows up so we can rightfully state that the situation for a grown-up person who was raised in this way stays the exact same. In other words, they are ‘enmeshed’ with their primary caretaker lifelong, whether that person is still alive or not.