只是配角而已何必入戏太深
[zhĭ shì pèi jiăo ér yĭ hé bì rù xì tài shēn]
This means, 'Being just a supporting character, why take it too seriously?' It expresses a feeling of disillusionment or resignation in a certain situation where someone doesn't feel they are the main character in their own life, often implying an unrequited love.