只一人只能自言自语
[zhĭ yī rén zhĭ néng zì yán zì yŭ]
Means 'Just one person speaking to oneself'. This portrays a sense of isolation - being unable to share inner thoughts aloud because no companion exists to converse with; resorting instead to soliloquy. This could arise from loneliness, introspection during periods without social interaction, finding solace through private conversations as opposed to outward engagement.