English Social Sciences General / Conversation / Greetings / Letters preoccupied attachment

Dear colleagues,
I’m not sure how to interpret “she had no core” right at the end of the following passage describing a woman who entered therapy out of concern that she might not marry or have children; she had characteristics of a preoccupied attachment pattern.
How do you understand “having no core” in this case? “Soul” may be too strong... what about “she had no center”? Although I think "core" may refer to something "stable" and "well-defined" in this case, but I'm not sure...
Thank you very much for any suggestion!

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Approaching 40, Ellen came into therapy out of concern that she might not marry or have children. She had married impulsively when young and divorced within a year. Since then she had had several relationships to which, when push came to shove, she had not committed. She could not understand why.
Poised, professionally successful, and engaging, she exuded confidence and had what she called a “bright personality” that “came naturally.” Indeed, she had hypomanic character traits that defended well against depressive states and an array of repressive defenses that defended successfully against anger. The immediate precipitant for her coming to therapy was that for several months she had had unexpected “fits of tears” while alone at home. They marked moments when panic about not marrying or having children broke through her defenses. Well motivated, from the first session on, she entered the room raring to go. (..)
Ellen had characteristics of a preoccupied attachment pattern. (...)
She told me that she felt like a balloon with its air escaping, sputtering around in fits and starts, giving her a sense of fragmentation. (In her initial interview, *** Ellen told me she sometimes felt she had “no core.”)***