Meaning- either partner in marriage.
Usage- He doesn’t make any decision until check with his better half.
Origin- Puritans were English Protestants in the 16th and the 17 centuries who favoured strict religious discipline. They said each person was made up of two halves, body and soul and the soul was the better half because it was the spiritual side.Sir Philip Sidney an English writer, said that a marriage was made up of two halves,and the better half was the better spouse. Today when the phrase “better half ” is used ,it almost always means someone’s wife, although there is no reason why a wife can’t use the term to describe her husband. In either case ” better half” is a compliment.