你是我存在的理由你是我活着的氧气
[nĭ shì wŏ cún zài de lĭ yóu nĭ shì wŏ huó zhe de yăng qì]
'你是我存在的理由你是我活着的氧气' implies 'You Are The Reason For My Existence And My Oxygen'. It shows how essential a person is, similar in sentiment as being indispensable like air to the person speaking.