Need is a weak word. Has nothing to do with what people get. Ain't what you need that matters. It's what you do.
Haven gives his son this advice when his son is complaining about how much he needs a store bought coat. It is also the underlying message in everything that Haven teaches his son. It all comes back to taking what you get and doing what had to be done. No matter how much Robert needs Pinky, he finally realizes that there is nothing he can do to stop what has to happen. There are numerous other instances of things that Robert thinks that he needs that he does not get. When Robert learns to accept what he gets from life and do what needs to be done, he becomes a man. Seeing that Robert is a man, and he is no longer needed, Haven is allowed to die in peace.