- A psychologist coined the term "limerence" to describe extreme, uncontrollable longing
- Brain imaging has found a relationship between passionate love and the reward hormone dopamine
- One expert thinks the suffering combines an obsessive-compulsive reaction and an addiction
After a breakup there's the expectation that you'll eventually move on. But what if you can't? What if the impulse to think about an ex became all-consuming -- months, even years later? What if it never goes away?