insociable

/ɪnˈsoʊʃəbəl/
adjective
  1. Not sociable; unwilling or unable to enjoy the company of others; unfriendly.
    • The old man was known as an insociable neighbor who never attended community events.
    • The new student seemed insociable and spent all his time alone in the library.
    • Her insociable behavior at the party made guests uncomfortable.