我是笑得多开心她才会伤心
[wŏ shì xiào dé duō kāi xīn tā cái huì shāng xīn]
“Wo shi xiao de duo kaixin ta cai hui shangxin” translates to 'I smile so happily, and only then she feels hurt'. It implies a complex emotional relationship, indicating an opposite feeling between oneself and the other person; one's joy brings pain to another.