What does she mean by this?

Hey, I recently asked my ex why she kept staring at me during classes together, I thought it was a good idea to get to know why, otherwise I'd be thinking of all the possibilities she'd do so. She told me that she doesn't know and she cannot explain it and that I should not hate her after I said I would (as a joke) if she wouldn't tell me. So can anyone help me by what she means by the 'cannot explain' bit. I'm not sure if she likes me or not, knowing will clear the loom of confusion so any help will be good thanks.