Last Topic: 11:26:45am, 06/22/2018
Last Post: 7:01:32pm, 02/20/2018
It's just a way of talking about some one's partner when you don't know if their partner is their wife, boyfriend, transsexual dominatrix, and so on.
Why use it instead of "partner"? Because language is dumb and terms always fall out of common usage and are replaced by other terms.