The person who discovered the law of love was a far greater scientist than any of our modern scientists. Only our explorations have not gone far enough and so it is not possible for everyone to see all its workings.
For me, the greatest source of frustration was trying to work with a willful child when there was something else I wanted - say, to get the child to go to bed so I could have my own time. Just the promise of the time, and feeling that promise slip away, was enough to introduce a whole other element of stress into the encounter.