微笑使结局变得更加忧伤
[wēi xiào shĭ jié jú biàn dé gèng jiā yōu shāng]
This means 'A smile makes the ending even more sad.' Here, it expresses an irony where smiling, which usually denotes happiness, actually enhances the melancholy of the end, possibly hinting at a bittersweet situation, where joy only serves to make eventual loss more poignant.