Obsessing over loneliness is a key factor in the development of depression

"...ruminating on the feeling of loneliness is the key underlying factor that explains the adverse effects of loneliness in the generation of depression"

This doesn't suggest that gratitude is necessarily the prescription. Rather, activity. If you spend your time doing engrossing things, then you're less likely to become depressed - and (I would argue) more likely to meet interesting people.