Don't do or say anything you'll regret. BPD makes you think you did something to cause the momentary separation. It goes back to abandonment in childhood. A child is still mentally egocentric. The developing brain is too primitive to understand concepts such as people having other goals or still having that connection despite not being presently there in the moment (this is called object constancy, infants don't have it). So the reaction formed in the child's mind is that "Mom/Dad abandoned me because I'M BAD", and this forms the core abandonment complex in BPD as well as the low self-worth and hypersensitivity. It's amazing how it plays out in adulthood. People with BPD have parts of their personality still stuck in very early childhood and it takes time, mistakes, pain and therapy to help those parts mature.

I know this all cognitively, I emotionally can't grasp it fully yet. I can spot myself when I have moments like the one you are describing, but it's like watching a car accident in slow motion.