Broken heart

A broken heart (also known as a heartbreak or heartache) is a term metaphor for the intense emotional—and sometimes physical—stress or pain one feels at experiencing great longing. The concept is cross-cultural, often cited with reference to a desired or lost lover, and dates back at least 3,000 years.

Emotional pain that is severe can cause 'broken heart syndrome', including physical damage to the heart.

The emotional "pain" of a broken heart is believed to be part of the survival instinct. The "social-attachment system" uses the "pain system" to encourage humans to maintain their close social relationships by causing pain when those relationships are lost. Psychologists Geoff MacDonald of the University of Queensland and Mark Leary of Wake Forest University proposed in 2005 the evolution of common mechanisms for both physical and emotional pain responses and argue that such expressions are "more than just a metaphor". The concept is believed to be universal, with many cultures using the same words to describe both physical pain and the feelings associated with relationship loss.

The neurological process involved in the perception of heartache is not known, but is thought to involve the anterior cingulate cortex of the brain, which during stress may overstimulate the vagus nerve causing pain, nausea or muscle tightness in the chest. Research by Naomi Eisenberger and Matthew Lieberman of the University of California from 2008 showed that rejection is associated with activation of the dorsal anterior cingulate cortex and right-ventral pre-frontal cortex, areas established as being involved in processing of pain, including empathizing with pain experienced by others. The same researchers mention effect of social stressors on the heart, and personality on perception of pain.

...
Wikipedia