The reason why hearts break is they never see it coming.
The mind does.
The mind knows nothing lasts forever. It knows there may come a day when love — generously given today — is completely withdrawn tomorrow. With no sign, no warning.
So, the mind braces itself for impact. And when that fateful day arrives, it knows how to bend. It knows how to deflect a lot of the agony and pain.
But the heart does not. It never sees it coming. It can but break.