相見恨晚

相见恨晚
xiāngjiànhènwǎn
  1. to regret not having met earlier (idiom); It is nice to meet you finally.
  2. It feels like we have known each other all along.

CEDICT

to regret not having met earlier; if only we had met earlier (used to express the happiness when meeting with someone for the first time)

Wiktionary

遺憾認識得太晚。語本《史記．卷一一二．平津侯傳》：「天子召見三人，謂曰：『公等皆安在？何相見之晚也！』」形容一見如故，意氣相投。宋．方千里〈六么令．照人明豔〉詞：「當時相見恨晚，彼此縈心目。」也作「相逢恨晚」。

重編國語辭典

指想要遇到的事情，遺憾相識太晚，已經錯過了良好時機

維基詞典

Entry Composition

1 相見 xiāngjiàn
  1. to see each other
  2. to meet in person
2 恨 hèn
  1. to hate
  2. to regret
3 晚 wǎn
  1. evening
  2. night
  3. late