First, you need to decide what you want to call your partner - wife, life partner, significant other, etc.
It sounds like your entire office are repeat offenders.
Give the asker a puzzled frown (to convey disapproval) and say "Do you mean my (wife, life partner, significant other, etc.)?" When they confirm that they mean your partner, give them an update, thank them for inquiring, smile, and say "Please refer to (her name) as my (wife, life partner, significant other, etc.) - she's not just my friend." Frowning as a reaction to their behavior and smiling when you model the proper behavior will help set the message in their heads.