odd form behavior on relationship

$this->form->fill([
            'accountNote' => ['notes' => ''],
            'preparer_comments' => ''
        ]);

public function showEditModal($id)
    {

        // Fetch the row data based on ID
        $this->editItem = BalanceSheet::find($id);
        // dd($this->editItem);
        $this->form->fill([
            'preparer_comments' => $this->editItem->preparer_comments,
            'accountNote' => $this->editItem->accountNote //can't seem to set just the field on this, have to set the entire relationship.
        ]);

        $this->dispatch('open-modal', id: 'editRowModal');
    }

public function form(Form $form): Form
    {
        return $form->schema([
            Grid::make()
                ->columns(1)
                ->relationship('accountNote')
                ->schema([
                    Textarea::make('notes')
                        ->label('Account Notes')
                        ->rows(6),
                ]),
            Textarea::make('preparer_comments')
                ->label('Preparer Comments')
                ->rows(6),

        ])->statePath('data')
            ->model(BalanceSheet::class);
    }