The world is divided into two. People who have experienced this traumatising phenomenon, and people who haven't.
There is nothing that distinguishes these two classes... both princes and paupers have experienced heartbreak. Both the most learned, as well as the very most plebian, may experience this.
Essentially heartbreak occurs when something stops the flow of sweet lovin' from a person's significant other. It could be death of the afore mentioned S.O. or perhaps betrayal, or simply the lingering demise of a relationship that wouldn't work out, but was dragging alot of pain and suffering along with it as it got spent.
Hearts are fragile. Nobody's heart is too strong, too hard, too taut to be broken. You can feel perfectly O.K. one minute and then something, in a mere second, can cause your heart to break and things come crashing down around you and you are left in a heap of shatterred dreams.
And the shocking thing about this is that it actually feels like there is something wrong in your chest... one experiences a heaviness, or a sharp twinge of pain ever present in the region. It is not something over-zealous poets have sat and though about... it is something really there, actual documented pain.
As yet there is no cure for heartbreak. Time, they say, is the best healer... but one might add that Time more than heals, makes you forget, and with forgetfulness comes some peace.
However no one fully recovers.