My simplest script is often the best: Babe, tell me why you are upset with me. I don't like it when you are being mean, especially when I don't know why.
is correct. We do know why. U2 wears sexy lingerie for some combination of the following:
1. She feels guilty for rejecting U. She feels it is U's fault that she feels guilty (if he did not continue to desire sex, she would not feel guilty). She wants to punish U for making her feel guilty. So she teases him by wearing sexy lingerie even though she has no interest in having sex and would reject him if he initiated. She sees this as a fitting almost poetic "justice" for his mistreating her by triggering her guilt.
2. She likes feeling desired and desirable. She dresses up to allow U to show that he still finds her sexy.
3. She likes knowing that U remain under her thumb / thrall / control. She likes seeing U react to her dressing sexy because it means he is still tied to her. Still committed to staying married to her. If he decided to leave, his reaction to her would be very different. Her getting a "rise" out of him by dressing sexy confirms he hasn't decided to leave.
We all know this is 100% about power and control and nothing about sex or sexiness or her desire for sex with U. In fact it is quite the opposite. Her desire to dress up in sexy lingerie arises directly from her LACK of desire to have sex with U. It is sick and twisted, but quite common and understandable and actually quite rational when viewed from inside her dysfunction.
U does not need to ask her why she does this, because in reality he already knows. And he also knows she will never admit the truth. So there is no point in asking. In fact, asking is a weak move because in the end he will undoubtedly accept her total BS responses which will only further reduce her already pitiful lack of respect for him.