Sometimes when we help someone, we expect gratitude or some instant reward for our good deed. If that person is not thankful enough, we consider him ungrateful or hard hearted.
I strongly feel that if we help someone, we should pray that Allah gives us the reward for our good deed because what Allah can bless us with no human being can give.
Similarly if someone hurts us, we should pray to Allah to recompense us for that loss because it is beyond human capability to erase the hurt and loss unless Allah gives us something that is better even if it peace and contentment of heart.
My point is, we look towards our fellow human beings too much while we should focus on strengthening our relationship with Allah for a serene, happy life.