There is a position in many yeshivas called a "mashgiach ruchani". His job is to make sure that all of the boys are davening and learning as they should. Part policemen, part judge, part parent.
Many wives think [unconsciously] that they must serve as mashgichos of their husbands after marriage. This is a fundamental and potentially catastrophic error. NO HUSBAND WANTS A WIFE WHO SERVES IN SUCH A ROLE and therefore anything she says will only create friction and tension. A man wants a wife who will love, encourage, appreciate and respect him. He also wants dinner [ועי' שלחן ערוך או"ח סי' ר"מ והמבין יבין]. If a wife does those things peace will reign in the home. If she wants him to change a certain behavior, positive encouragement and subtle hints are the correct approach. Criticism doesn't help and only serves to annoy the husband and frustrate the wife when he is not changing. It has already been said that the last time a woman changes a guy is when he is wearing diapers... [that is a FUNNY line! Please laugh. Thanks!!]
As I write I already imagine the emails the ladies will send me asking about husbands who act as their wives mashgichim. Is THAT ok? Why the double standard?
The fact is that this is WORSE than the other way around. One of the dumbest things a man can do. If she wants your mussar, she'll ask for it. If she wants, she can go to a shiur and hear mussar from someone who is not her husband. She is much more likely to be receptive to someone else. From her husband she wants love, validation, acceptance, understanding, help around the house and ... a credit card.
So if she is wearing a skirt you think to short [a STRANGE yetzer hara that I can't understand, I NEVER felt like wearing a short skirt, even in my more "modern" days] or focusing too much on the interior design of the house and not the interior design of her soul DON'T GIVE HER A MUSSAR SHMOOZE. It'll cost you big... What you can do is appreciate her more modest look and compliment her when she is focusing on matters of the spirit.
Thoughts that if taken to the heart will result in a fulfillment of the pasuk וידעת כי שלום אהליך