兩人成伴，三人不歡。

Two's company, but three's a crowd.

Source: Tatoeba

Sentence Composition

=1 兩 liǎng
  1. two
  2. both
  3. some
  4. a few
  5. tael, unit of weight equal to 50 grams (modern) or 1⁄16 of a catty 斤 jīn (old)
=1 兩 liàng Original form of 輛／辆 (liàng).
2 人 rén person; people

classifiers: 個, 位
=3 成 Chéng
  1. surname Cheng
  2. short name for Chengdu 成都 Chéngdū
=3 成 chéng
  1. to succeed
  2. to finish
  3. to complete
  4. to accomplish
  5. to become
  6. to turn into
  7. to be all right
  8. OK!
  9. one tenth
=4 伴 bàn
  1. partner; companion; comrade; associate
  2. to accompany
=4 伴 pàn
  1. (obsolete on its own in Standard Chinese) alternative form of 叛 (pàn, “to rebel”)
  2. (obsolete on its own in Standard Chinese) used in 伴奐／伴奂 (pànhuàn, “relaxed; free; unrestrained”)
  3. alternative form of 叛 (pàn, “to rebel”)
  4. used in 伴奐／伴奂 (pànhuàn, “relaxed; free; unrestrained”)
=5 三 Sān surname San
=5 三 sān
  1. three
  2. 3
6 人 rén person; people

classifiers: 個, 位
7 不 bù
  1. no; not so
  2. (bound form) not; un-
8 歡 huān
  1. joyous
  2. happy
  3. pleased