Some people assume if someone smiles a lot and is outgoing, they're happy, but if they're introverted and sorta serious and don't smile much, they... Show More
Most Helpful Girl
Lots of reasons... introverts aren't fulfilled by social interaction, so they don't see much point in giving a fake smile or fake hello to everyone who crosses their path. They also aren't interested in talking to everyone, so they may adopt facial expressions that seem "standoffish" or "unhappy" to prevent other people from trapping them in random conversations. A lot of it is probably unconscious, and it's rarely a sign of true unhappiness or dislike of other people. Most introverts are perfectly happy, and have many wonderful, deep relationships with others, but they really like to be left alone too.