Can't we argue this is true for all "bad" feelings? If they were utterly useless, why would they still exist? They have a function. Love and grief is basically

Can't we argue this is true for all "bad" feelings? If they were utterly useless, why would they still exist? They have a function. Love and grief is basically akin to "what goes up must go down". No high without the low, like the rollercoaster life is.