“Jeremy was the last person she had left, so it's very likely that Elena could go off the deep end now that she doesn't have the one thing that kept her human,” says Nina, adding, “It's going to destroy her.”
Part of the problem is that Jer has come back from the dead so many times already; the elder Gilbert sibling will try anything and everything to bring him back. Nina says, “Elena is basically mentally unstable, going a little crazy, and everyone is trying to help.”
Then Nina hints that the grief will fundamentally change Elena. “It's an Elena we haven't seen before, and you'll be shocked, quite frankly,” promises Nina.
Elena the Ripper? That would definitely be shocking — but not something we’re sure the compassionate vamp could recover from.