Morality and happiness are two different domains of study and discussion. The ethically correct belief or action is no guarantor of happiness, nor is happiness a guarantor of ethically correct beliefs or actions. Simply put: ethical people can be miserable, and happy people can be unethical.
Yet these two subjects are sometimes intimately tied to one another. Consider, for instance, a recent essay by Jonah Lehrer in which Lehrer synthesizes a couple studies that suggest humans are happier (happiness) when wealth is more equally distributed rather than less equally distributed (ethics). As Lehrer writes:
The scientists speculate that people have a natural dislike of inequality. In fact, our desire for equal outcomes is often more powerful (at least in the brain) than our desire for a little extra cash. It’s not that money doesn’t make us feel good — it’s that sharing the wealth can make us feel even better.