Wife or husband-
Persons with whom one is married
Person who joins the spouses program, the kindergarten for Important Meetings.
Person who has a business relationship with a loved one.
Better Half -
Said by a person who claims false modesty. He doesn't ever believe she is better, nor that he is only half.
Significant Other -
The least meaningful term of them all! It may be the dog, or the gerbil, or the tick that bit me. Significant other reduces a person to a mere nothing, a term, no more.
How insignificant can one be?