She may be afraid that YOUR positive changes, H4U, are going to disappear now that she's had sex with you.
It's important how you handle this time. DON'T ACCUSE; just ask her, and listen. And if she's NOT comfortable with MLing with you right now, as much as that would sukk, make DAMNED sure you keep up ALL of your positive changes . . . and then some . . . for some period of time (1-2 months?).
