This paper examines the function of psychological pain for the human psyche and how this function affects our mental health. We apply realistic methodology in a critical interpretive synthesis, which allows us to identify and analyze relevant theoretical and empirical re- search. An examination of identified social pain research resulted in the identification of neurological and physiological mechanisms and processes involved in social and psycho- logical pain processing. An analysis of research on this topic enabled us to identify how these processes interact through feedback-loops to facilitate psychological pain processing. This led to the conclusion that the function of psychological pain is to inform humans of potential social threats, which allows us to initiate emotional and behavioral changes to accommodate these. Furthermore, this led us to conceptualize our understanding into an evolutionary hypothesis of a compiled psychological protection-system that facilitates the psychological pain function. This enabled an analysis of how the psychological pain func- tion can be regulated or dysregulated by neurological and physiological mechanisms as well as emotion-regulation, motivation and attachment and socialization processes. Fur- thermore, this protections-system allows us to answer how our mental health is affected by psychological pain; through the regulation or dysregulation of the protection-system. Hereby we can conclude that continued psychological pain can have a dysregulating effect on our mental health. In relation hereto we also conclude that some psychological pain serves a function, while some doesn’t. This perspective is discussed through its clinical implications.