分手之后的思念叫犯贱
[fēn shŏu zhī hòu de sī niàn jiào fàn jiàn]
Literating meaning 'The nostalgia post-breakup is deemed foolish'. Here, missing an ex after parting ways is referred to negatively as stupidity, criticizing such sentimental attachments which reflect irrationality especially concerning former partners causing emotional vulnerability and regretful dependency.