無緣無故

无缘无故
wúyuánwúgù
(idiom) no cause or reason; completely uncalled for

CEDICT

without cause or reason; for no reason at all

Wiktionary

沒有任何原因或理由。

重編國語辭典

沒有任何原因或理由

維基詞典

Entry Composition

1 無緣 wúyuán
  1. to have no opportunity
  2. no way (of doing sth)
  3. no chance
  4. no connection
  5. not placed (in a competition)
  6. (in pop lyrics) no chance of love, no place to be together etc
2 無故 wúgù without cause or reason