  Loneliness has been associated with negative outcomes for physical and mental
health. Understanding how people express and cope with various forms of
loneliness is critical for early screening and targeted interventions to reduce
loneliness, particularly among vulnerable groups such as young adults. To
examine how different forms of loneliness and coping strategies manifest in
loneliness self-disclosure, we built a dataset, FIG-Loneliness (FIne-Grained
Loneliness) by using Reddit posts in two young adult-focused forums and two
loneliness related forums consisting of a diverse age group. We provided
annotations by trained human annotators for binary and fine-grained loneliness
classifications of the posts. Trained on FIG-Loneliness, two BERT-based models
were used to understand loneliness forms and authors' coping strategies in
these forums. Our binary loneliness classification achieved an accuracy above
97%, and fine-grained loneliness category classification reached an average
accuracy of 77% across all labeled categories. With FIG-Loneliness and model
predictions, we found that loneliness expressions in the young adults related
forums were distinct from other forums. Those in young adult-focused forums
were more likely to express concerns pertaining to peer relationship, and were
potentially more sensitive to geographical isolation impacted by the COVID-19
pandemic lockdown. Also, we showed that different forms of loneliness have
differential use in coping strategies.
