Because she didn’t or doesn’t? You can’t make a generalization off of one time. Whether she was right or not in dressing the way she did doesn’t allow for a generalization.
Is there a shadchan involved? Maybe speak to the shadchan and see if they can shed light and possibly give a reason? Maybe speak to someone the girl and you know that can act as an uninvolved outside observer?
😀 Zuberman! 😀