一种难以诉说叫相思一种不愿提起叫回忆
[yī zhŏng nán yĭ sù shuō jiào xiāng sī yī zhŏng bù yuàn tí qĭ jiào huí yì]
There's a longing that's hard to express, known as yearning or ‘xiangsi’, and there's also reminiscence one doesn't wish to recall called memories. This suggests complex emotions of unexpressed desires or difficult past experiences the person would rather forget.