publish content fragment on AEM 6.4

This means the CF itself may not exist on Pub. It would be like a component. If that component does not exist on the PUB instance, then it will not show up in the page being served from a PUB instance.

The CF was not published, and when i manually published the CF, the page worked.

so every time i use a CF in my page it will be necessary to upload the CF manually, right?
but when i publish my page, all the content shouldn't be published together?

Like components - you need to get them into the publish instance. You can use Packages for this purpose.

Publishing pages that contain CF will not automatically move them to the Pub instance.

Ok, Thanks.

Here;s what I found -

When you publish a page that reference a content fragment that was modified but not published yet, then the publish screen will show you all the references to Content Fragments so that Authors are enabled to publish them.

On the other hand, when publishing a content fragment, authors would not know the pages that are referencing that content fragment.

I wish at least the references can be shown as it currently does for an image asset - 

Please correct me if my understanding is wrong.

If my Content Fragment has a content reference to an asset for example an image which is yet not published and if I publish my page , AEM asks for content fragment to publish but it doesn't ask for the image asset to be published.

Is there a way to configure such thing so AEM also asks for the image referred in content fragment to be published when I publish my page ?

That would be a transitive reference, and of course checking these is also possible. But depending on your content this will take longer. Though, it should not be too hard to implement, see [1] for a way to implement such a ReferenceProvider.

[1] acs-aem-commons/PagesReferenceProvider.java at master · Adobe-Consulting-Services/acs-aem-commons · GitHub