HUMAN EMOTION: SADNESS
Humans form strong bonds with each other known as relationships. They appear to be the specie's strongest catalyst for emotion, other than art.
One kind of relationship between a "boyfriend" and "girlfriend" is called dating. It's a ritual of going out to eat together at Olive Gardens, playing miniature golf, and fondling one an other's sexual organs.
When the bond between boyfriend and girlfriend, or lovers, is no longer valid the practice of "breaking up" commences. This process can take anywhere from a few minutes to years to be completed.
It is during this transaction that one or more of the humans expresses the sadness emotion. It can be very powerful. Even evoking other emotions like anger. The whole operation seems to part of healing method to bring the humans psyche back to equilibrium.
Let us observe this trait in a male subject ripe with emotion sadness. Notice the furling of his brow, the sternness of his eyes, and how the corners of his mouth turn downward. These signs appear to be consistent with our findings. One symptom of sadness that seems to be absent in "Ricky" is crying. Although, it can be inferred that he probably does this consistently into his pillow at night.