Well, I'm sure she is making some kind of statement, but showing her knickers is not the best way to make a statement. I would ask her to sit down with you and discuss whats happening in your marriage. She doesn't seem to be happy.
My wife has started to wear very short dresses and skirts of late, and she goes bare legged sometimes, which looks very slutty. I said what on earth are you wearing? Your knickers are showing a little. You are 43 not 16 -she laughed. What can I do?