日久生情

rìjiǔshēngqíng
familiarity breeds fondness (idiom)

CEDICT

  1. (wordplay, vulgar, slang) to develop fondness after sleeping with each other for a while
  2. familiarity breeds fondness; love develops with time
  3. to develop fondness after sleeping with each other for a while

Wiktionary

人与人相处时间一长，自然会产生感情。通常用于男女之间。

重編國語辭典

  1. 一起睡觉一段时间后产生好感
  2. 人与人相处时间一长，自然会产生感情

維基詞典

Entry Composition

1 日久 rìjiǔ with the passage of time; over time
2 生 shēng
  1. to be born
  2. to give birth
  3. life
  4. to grow
  5. raw
  6. uncooked
  7. student
3 情 qíng
  1. (bound form) feelings; emotion; sentiment; passion
  2. (bound form) situation; condition