If the heart had been aware of the beloved's fickle and changing nature, it would never have grieved over the double-dealing of the world.

The poet draws a poignant parallel between the beloved's fickle temperament and the world's deceitful double-dealing. He suggests that if the heart had already been familiar with the beloved's ever-shifting moods, the world's hypocrisy wouldn't have stung at all. Surviving the sweet yet painful deceptions of love naturally immunizes a person against whatever betrayal the rest of the world has to offer.