“The only possible society is oneself.”
The comic exaggeration makes self-company part of Wilde’s joke about society while still centering comfort with oneself.
Source details
An Ideal Husband, Act III; Lord Goring tells Phipps “The only possible society is oneself” immediately before the lifelong-romance epigram. Verified against the public-domain Wikisource Act III transcription and Project Gutenberg #885; the line remains dandyish comic character speech rather than uncomplicated authorial doctrine.