confidante
  知己的女友
  Con·fi·dant 277), n. masc., Con·fi·dante n. fem.  One to whom secrets, especially those relating to affairs of love, are confided or intrusted; a confidential or bosom friend.
  You love me for no other end
  Than to become my confidant and friend;
  As such I keep no secret from your sight.   --Dryden.
  ◄ ►
  confidante
       n : a female confidant