I've been trying to put myself in Elizabeth's position, see it from her eyes, hoping it will shed some light.
So far, a lot of this is based on nothing but personal belief and the fact that I am very close to her age and I think I understand some of what she thought and felt prior to December. At that point, she becomes alien to me. None of this is said to offend or to excuse EJ's actions.
She's 23, and not an old 23, either. She seems very street smart (even the smart ones make mistakes), and also book smart, but not very people smart. It would be easy for her to find a predator and easy for one to convince her that they aren't a predator.
She has anger issues, obviously. That was a lot damage to the apartment, and it was not just blind rage. If she had just broken some dishes and then gotten herself together, that wouldn't bother me as much. (I have thrown a few dishes in my time.) She burned through blind rage, and kept going, methodically cutting up clothes, yet apparently not doing any damage to herself.
This rage was apparently, according to one article at least, was because he was late. That shows she is territorial over her life as she has chosen it. This is typical with foster kids, especially those that had no control over their own placements.
She has no real emotional depth. I am not branding her a sociopath yet, I believe the term is overused and misunderstood. She is just a shallow human being. She wanted to hurt Logan, that much is crystal clear. But the issue for me is whether she understands how much, and if she able to understand how much the death of a child is supposed to hurt. I don't believe she does. She never bonded to Gabriel, she does not feel like a mother, so she can't understand the feelings of a parent losing a child. She likely, even if Gabe is dead, doesn't see this as that painful, although it may hurt, just not as we feel it should. Her emotions don't process like that.
She doesn't care about herself in any meaningful kind of way. She has no long term self preservation instinct. She thinks about tomorrow, that's an attainable future. Thinking about next year, or 20 years from now, very rarely. That would be partially the foster system, partially whatever behavioral issues of mental illness she does have. (Whatever label will be put to it.)
So, if I were to look at Elizabeth just by herself, away from the other details of the case, I would see a gullible, shallow, defensive, controlling, angry, emotionally delayed, spiteful and intelligent young woman. And I would assume that Gabe were dead. However, based on all of the above without the other details of the case, I would have also assumed that she killed him before she left Tempe. The unknown is why she didn't. And that is the part of her personality I can't pin down, and that is the part that gives me hope he's still alive.
ETA: Not to interrupt the flow of conversation, but I had to get up several times while typing this and the board moved on without me. lol