难再得久不遇
[nán zài dé jiŭ bù yù]
'Rare Encounter Difficult To Repeat Over Long Time' expresses rarity, uniqueness, and cherishness towards moments or encounters that one has had. '难再' highlights difficulty repeating, '得' signifies obtain, '久不遇' portrays a very long time without meeting again. So, the overall implication here lies on valuing infrequent meetings which become precious over time.