你是我不可触及的底线
[nĭ shì wŏ bù kĕ chù jí de dĭ xiàn]
It refers to 'you are my untouchable limit/ bottom line'. It depicts someone who has transcended the limits set in their mind for personal relationships, indicating they care about this individual more than any other and would be reluctant or incapable of crossing certain emotional lines or limits.