Wears the pants

Generated image of a woman wearing a pant suit
To wear the pants means to be the person who has the most authority or control in a relationship or group. It usually describes the person who makes the main decisions.

The expression comes from older social customs when trousers were traditionally worn by men and were associated with authority in the household. Over time the phrase became a general way to talk about who is in charge.

Everyone jokes that she wears the pants in their family because she is the one who makes all the big decisions.