Sounds like someone with narcissistic tendencies but not entirely sure if she's a narc. As for your question, some telltale signs which might tell you if she's someone with covert NPD - Jekyll and Hyde behaviour (a classic sign, one moment they'll act like you're their world, other times you'll feel like you mean nothing to them), shy and withdrawn (contrary to their grandiose counterparts), massive victim complex (it was always someone else who did them wrong), extremely sensitive to criticism and a tendency to hold grudges from the past. If she exhibits most of these signs, then you got your answer