There's no way she'd put her parents and siblings through this. I just don't see it.
I could imagine her leaving, nut I would expect a note. And maybe a call to mom. But the real teller on that one is her driver's license. I can imagine her leaving it all behind and running off with the "real dad" leaving her purse, phone, car, etc... but she would take her driver's license and probably some cash.
If the DL is in the purse with everything else, she didn't run off.