I can relate to many parts of what you are sharing in your story here. No pet names for me, but some references to inside "jokes" that are along similar lines. This is really difficult to figure out where the boundaries are. The part of noticing how it can be comfortable for the WAS is really true. The struggle--for me anyway--is in trying to ascertain what it means: is it just as far as it will go? Is it a foundation for something more? How to explain the pet names thing...I suppose it can only reflect some confused or ambivalent feelings.
How do you feel about the pet names thing? What do you make of it?