风情万种曲终人散
[fēng qíng wàn zhŏng qŭ zhōng rén sàn]
After the show of endless allure or charm has come to an end, only loneliness or parting remains ('all is gone'). It can refer to after moments filled with joy, warmth, or romance have faded away, reality becomes empty, sad, lonely, suggesting an elegy or melancholy.