That you can literally die of a broken heart.

Heartbreak is usually associated with losing a spouse or loved one, though losing a parent, child, pet, or close friend can also "break one's heart". The phrase refers to the physical pain one may feel in the chest as a result of the loss. Although "heartbreak" is usually a metaphor, there is a condition -- appropriately known as Broken Heart Syndrome -- where a traumatizing incident triggers the brain to distribute chemicals that weaken heart tissue.