How did "bitching" get associated with talking behind people's backs or complaining?

"Bitching" can refer to complaining or talking behind someone's back. But a bitch is a female dog which has nothing to do with it.

How did "bitching" become representative for complaining or talking behind someone's back? Is there history behind this use?

Solution 1:

TO bitch (intransitive):

• To criticize spitefully, often for the sake of complaining rather than in order to have the problem corrected.
  • All you ever do is bitch about the food I cook for you!

(Wiktionary)

According to Etymonline the sense may derive from the Middle English "bicched" meaning cursed, bad!

Bitch (v.):,

• "to complain," attested at least from 1930, perhaps from the sense in bitchy, perhaps influenced by the verb meaning "to bungle, spoil," which is recorded from 1823. But bitched in this sense seems to echo Middle English bicched "cursed, bad," a general term of opprobrium (as in Chaucer's bicched bones "unlucky dice") , which despite the hesitation of OED, seems to be a derivative of bitch (n.).