旧愛新歡
[jiù ài xīn huān]
'舊愛新歡' refers to the concept of comparing past romances with current/new ones. 旧爱 (jiù ài) is love affair(s) once cherished; 新欢 (xīn huān), new source(s) of joy - thus the overall meaning is about contrast between ex-lovers or lovers and present day romance, suggesting a theme on nostalgia versus fresh start.