Relationship breakups affect the brain almost exactly like a physical burn does — in fact, the same areas and brain networks are activated when a person goes through a breakup or even thinks about one afterward as are activated do when the person touches a hot stove.
More facts about how breakups affect the brain:
The brain also experiences a withdrawal during a breakup that is very similar to a withdrawal from drugs or alcohol. In fact, the exact same areas of the brain associated with rewards, addiction cravings and physical pain are activated during a breakup as during withdrawal from an addictive substance.
It appears that going through a breakup can actually re-wire your brain. While going through the process of grieving a breakup, the synapses and dendrites of the brain can actually retract and reform into new patterns.
Sadness over a breakup appears to be neurologically different from other kinds of depression or grief. Though some similar parts of the brain are activated during a breakup and during a period of depression or grief, several different ones are activated as well.