I have a df who always does this to me it seems false and performative not to mention bloody annoying. So she will say something like do you ever see what's her name I will say who she will then go on to tell me great detail about this person all dc names and ages name of dh name of dog where they work and live but still claim not to know persons name. I know she will go to these lengths because today I pleaded ignorance of who she was talking about. Aibu to find this very performative and attention seeking.
FYI her name was clare so not difficult to remember