我总是以第三者的形式爱你
[wŏ zŏng shì yĭ dì sān zhĕ de xíng shì ài nĭ]
This translates to 'I Always Love You As the Third Party'. It expresses unreciprocated love from a secondary role, perhaps as a friend or observer, indicating frustration in never being fully accepted as a primary love interest.