A man who is ungrateful is often less to blame than his benefactor.

Help can be given in a way that makes gratitude nearly impossible. A favour delivered with a flourish, or repeated until it becomes a standing account, or mentioned afterwards to others, leaves the person on the receiving end smaller rather than helped. What comes back is resentment, and the giver reads that as ingratitude without ever inspecting the delivery. The debt was made too heavy to carry.

If someone has not thanked you as you expected, look at how the help arrived rather than at their character. And when you give, do it in a way the other person can accept without cost: quietly, once, and without a running total.