How would you describe this couple? Do you know any?

I only know one real delta rational dual couple, and she might be Fi and he might be Si or Te or no subtype. They definitely have a subtleness about them.
What I am commenting on is a faulty paradigm that there are two parts to each couple - the very reserved I type, and the very outgoing and talkative E type. It seems in this situation there would be a mutual reticence....