I agree, I love the DLC but I didn't like not being able to see Christine one last time.
Or find Dean gambling/stealing in New Vegas. Lame...

I don't get why we can't have DLC followers in our main game. I know they could just have a few tweaks to make them a bit m,ore useful in the main game. Story wise it won't work but it still fun.
Besides it says in the ending slides that Christine won't think of the Courier until the Divide showdown.