[Alneyan]

Nothing *is* a source of unhappiness (or, more specifically, of going back to neutral happiness): if nothing happens, you will slide back to Neutral happiness, unless you have a *very* high level of Happiness (150%? 200%?).

If you have a UPC, your happiness will not slide, regardless of how low it is (45% happiness and an UPC III is enough to keep a stable happiness, and even slightly increase it).