I've never had a broken limb, but the process of mending it seems to be to put on a cast. This hard material designed to protect the broken area, to keep it in place while the natural course of healing takes place. The cast keeps the bone set properly, but it also is this tough shell so that if the fragile place is bumped or moved, the fragile place is largely unharmed. Of course, if your arm is broke then you really shouldn't move it until it's properly healed, this is also a function of the cast, to remind you of what you cannot do.
So I think it is when life breaks us. Our heart is flooded with hurt, whatever the source of heartbreak, we find ourselves retreating a little bit, throwing a cast onto our fragile places, a rigid guard to immobilize the damaged area while we breathe for a moment, regain our footing and wait for the natural course of healing to take place. The side-effects are far from ideal, but outweigh the cons of not allowing the healing to ever take place.
I've found myself in such a place a time or two, perhaps even now, but the path seems a little different each time. I suppose the key is to be patient, look for hope and look for opportunities to love those who need it, because I believe love begets love, and that's a good place to start.