save model relationships on a standalone form builder with repeater

 public function mount()
    {
        $this->customer = User::find(1);

        $this->form->fill([
            'notifications' => $this->customer->userNotifications
        ]);
    }

    public function getFormSchema(): array
    {
        return [
            Repeater::make('notifications')
                ->schema([
                    TextInput::make('notification')
                        ->hiddenLabel()
                        ->columnSpan(2)
                        ->disabled(),
                    Toggle::make('email')->label('E-mail'),
                    Toggle::make('sms')->label('Text')
                ])->addable(false)->columns(4)->reorderable(false)->deletable(false)->hiddenLabel()
        ];
    }

    public function getFormModel(): Model|string|null
    {
        return $this->customer;
    }

    public function save()
    {
        $this->form->model($this->customer)->saveRelationships();
    }