We trust it, but one day we end up on the ground. We trust people too. Will they disappoint? Yes. Will they break our hearts? Yes.
Will we disappoint and leave other's stranded or lonely or dissatisfied? We will. It's almost a certainty. We won't mean to, it will just happen. We may even break their hearts.
That's why forgiveness works. And it must work for everyone to work for anyone. If not, it's the unforgiving one who hurts and hurts.