Introverts are often called loners when they just tend to be more reserved and introspective. While extroverts are energized from social situations, introverts are drained by them and instead need downtime in order to recharge and feel mentally healthy.
But that doesn’t mean they don’t WANT to be invited to things, and that doesn’t mean they don’t feel incredible FOMO when they decide not to attend social gatherings. The struggle is so, so real.