maybe, you can say, 'better half'.
good wife is very common.
but, better half can be a reference to your wife/husband whom you have vowed to be as one with, as in a Union. However, you are giving the most favorable credit of the Union to your spouse as an extra loving gesture. It will never mean boyfriend/girlfriend. You have to be married before you can use the "My Better Half" phrase. Special Note, Men use it more often than Women.
Husband: Let me introduce you to My Better Half.
Wife: This is My Better Half. - Special note, Women don't use it as often as Men do. They usually just say "hubby", which also means "My Better Half".