LE hasn't indicated much of anything to be fair.
Leaving spur of the moment before a flight is poor planning.
Or, she felt she had no other recourse at that point.
Despite her parents' statement that they want her home, they are offering a reward of $1,000. That may be one of the lowest monetary rewards I've seen printed since the Old West. Many of us would offer that for a lost dog.
Did naughty Nadia do a bad, bad thing? And then, when push came to shove, she realized she couldn't go to Italy because she had to clean up her mess?
Obviously, that's all speculation and very likely wrong. But, something about the way she left the airport makes me think she made the decision on the tarmac. Not earlier.