他是薄荷会凉人心她是柠檬会酸人心
[tā shì bó hé huì liáng rén xīn tā shì níng méng huì suān rén xīn]
This translates to 'He is mint who cools the heart, she is lemon who makes it sour'. Using mint and lemon as metaphors to describe different emotions between him and her that can trigger different feelings.