In a novel that I am working on, the MC has lost her memory and had a personality change because of a head injury. She was separated from her family at the time of the injury. In the beginning of the book she is with her parents...... then the injury.......then memory loss......she is separated from her family and I do not discuss them again until she regains her memory fully at the end. I have written in small partial memories here and there but nothing to identify the family until the end. Will my readers feel a loss because they know the family in the beginning and the whole book goes by without them in it until the end?
No, I don't think that is a problem at all. It's a natural consequence of the events of the story. Many stories involving children show the parents at the beginning and then you never see them again.
Readers might initially miss the family but knowing the books premise they'd understand it. As long as there are other interesting characters to fill the missing ones it shouldn't be a problem.