It can be hard to really trust people in relationships, some people don't exhibit extreme issues until late into a relationship where you're too invested to just simply leave. I don't know her story but i'm guessing she's a terminally online neet with little irl friends and too socially deficient to go out and meet people and when you're young in that type of situation, you can easily latch onto people quickly and fear them going away. I don't know what her bf did but considering he supposedly has 2 felonies and has been doxxing the shit out of her he probably fucked with her pretty bad. Coming out of a relationship where you felt like someone actually loved you and was close to you just to face all of these crazy issues can be pretty traumatizing when you don't have the support group and ways to cope but I don't really know the full story, i'm just generalizing based on experiences from myself and people I know.