Failing to comfort a crying girl

I go out to brush my teeth, and I hear, distantly, what sounded like a sob. I track it down to the open door of a friend of mine, a girl with whom I am vaguely friendly and who I used to have a thing for, but what of that. Sitting in plain view, no lights on, on the floor, sobbing. What the hell was I supposed to do? Ignore her? Pretend like she's not there? Or be the White Knight, doing what one does when he sees a damsel in distress?

I opted for the latter, asking first the most stupidly obvious "are you ok?" question for lack of anything else, which I quickly covered by, "Do you want to be left alone." She shrugged, not even looking at me, and well shit, that put me in a hell of a position. I ended up standing there, totally helpless to help her, and her with no interest to share it with me, for about five, maybe ten minutes. I should have left her alone sooner than I did, but man, how do you do that without feeling like a heel, especially if she didn't expressly ask you to leave?

Well, if she doesn't close her door or move soon, with all the traffic of people going back and forth, sooner or later someone's gonna notice. Either way, of course it'll settle itself one way or another. Even still, I feel kinda crappy. If I couldn't help, I shouldn't have offered. But how could I just ignore her...?

I need to get some sleep.