"...and finally, I gave her a tear to shed. This is hers exclusively to use whenever it is needed."

Ok, so she cries whenever she needs to, and cries for no reason.

Therefore, sometimes she needs to cry for no reason just for herself.

Ok, but why does she need to cry for no reason for her... ... oh forget it!!

I'm intelligent, not a genius!

(Health Warning:  The above post was made in jest, anyone attempting to explain why a woman cries for no reason may experience sudden uncontrollable diarrhoea!)