I'm not satisfied with the name for this entry, but I wasn't able to come up with a better one. Regardless of what we call it, I think we should have an article on the topic. If anyone has naming suggestions, please leave them below.
Similar phrases (e.g. "income and happiness", "income inequality and happiness") do generate a fair number of hits.
"The relationship between giving and happiness" is another possibility.
psychology of giving?
That seems too broad - this is a more specific topic.