your other half

(one's) other half

One's spouse, romantic partner, or boyfriend/girlfriend. I'd love to come out to the bars with you after work, but I'd better check in with my other half to make sure we don't have any plans for this evening. The work retreat is meant to be for couples, so be sure to bring your other half!
See also: half, other
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

your other half

or

your better half

COMMON If you refer to your other half or your better half, you mean your husband, wife, or partner. They invited us out to dinner after the election because they said it was time they met my other half. It's a shame my better half isn't here. You'd have someone to gossip with. Note: These expressions are usually used humorously.
See also: half, other
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

your better/other ˈhalf

(informal, humorous) your wife or husband: I’ll have to ask my better half about that.
See also: better, half, other
Farlex Partner Idioms Dictionary © Farlex 2017
See also: