If the female is not having active interactions with either the male or the other female I would guess that it is a health issue. If she was in pre spawn behavior I would expect a change in the interactions with the other Apistos. It is possible that she is working on claiming the cave, however, normally this would include some sort of "claiming" behavior which you don't seem to have.
I would suggest close observation for a few days.
DC
I would suggest close observation for a few days.
DC