"Paired" is a really loose term and is usually defined by each person.
To me, a breeder, paired/bonded bith mean the same thing which simply means they have been housed together at least for at least a few weeks and get along together. This relationship can certainly fall apart when an anemone is introduced and one Clown wants it to herself. Over time they may or may not re-bond. Usually if you buy a breeding pair they won't lose that bond for anything. Though I've seen sone of the designer clown breeding pairs to have really loose bonds...they are kinda weirdos.