separation anxiety

The thought came to me today that babies get separation anxiety once they develop to the point of recognizing there is only one you with no suitable substitute. Only one mom, or dad. Only one center of their universe. And to not be there is traumatic for sure.

So this idea makes me wonder: do adults get separation anxiety? What would this look like? Have you even found yourself digressed to infancy where you don't realize there's only one you and to be away from that true you is a terrible, very sad, very scary thing?