I am writing a story about a girl who once was complete, but now has lost what made her feel whole. She has tried to replace it with the same thing but failed. Now she has replaced it with something else and is, in a way, complete but not entirely since she is still missing that one thing that could make her feel that way. So, I am looking for a word to describe that state of feeling entirely complete, and being complete... but then again no. I thought of, having the illusion of being complete, but it doesn't really fit my idea. Please help me.
This idea has the sense of lacking closure, where the situation (from the character's point of view) is missing full resolution (see especially senses 2 and 2.1 in the link). In literature, such a case witholds general emotional satisfaction from the character, as well as from the reader who might empathize with him or her.
I feel like your story has an interplay between the past and the present, so how about the word Saudade:
The famous saudade of the Portuguese is a vague and constant desire for something that does not and probably cannot exist, for something other than the present, a turning towards the past or towards the future; not an active discontent or poignant sadness but an indolent dreaming wistfulness.
Disillusioned: having lost faith or trust in something : disappointed that something is not as good, valuable, true, etc., as it had seemed
Disenchanted: no longer happy or satisfied with something
(Definitions from Merriam-Webster)
Saudade a feeling of longing, melancholy, or nostalgia that is supposedly characteristic of the Portuguese or Brazilian temperament. According to one sight I read it means a feeling of being almost whole or onging for an absent something or someone that one loves, but knowing that the object of longing might never return. Its a feeling that brings sadness and happiness Also one can have saudade of someone whom one is with, but have some feeling of loss towards the past or the future. there's also no direct English translation and I hoped this helps
How about 'a shadow of her former self'? Or 'no longer true to herself'.
How about 'depleted', lacking, or 'unsatisfied'.
Or 'compromised' you could say she is 'somehow compromised'.
Or incompletely satisfied. Inferiorly replenished.
Unsatisfactorily replaced, completed, or reconstructed.
Inadequately fulfilled. Badly repaired. Poorly refurbished.
Like a car with a different coloured door - repaired, functional, but somehow unsatisfying.
A 'shadow of her former self'.
A dancer with a broken but repaired leg.
Not as she once was. Not as she dreamed herself to be.
Shades away from her true colour, from her true sense of self.
You might be able to use 'disingenuous' which can carry the meaning of 'not true to self'.