Antonyms of loneliness:
association, companionship, company, converse, fellowship, society.
Examples of usage:
  1. Miss Hyde and I have missed him so much in our loneliness.
    "Wives and Widows; or The Broken Life", Ann S. Stephens.
  2. She and her mother had rarely been separated, and the suddenness and sadness of the present summons only added to the loneliness.
    "Half a Dozen Girls", Anna Chapin Ray.
  3. And, worse than this, she was so hard- hearted that she took Rapunzel to a lonely desert place, and there left her to live in loneliness and misery.
    "The Red Fairy Book", Various.