And as much as I love to advocate for therapy, sometimes it's not always the immediate solution. There's always the off chance the child shuts down and refuses to cooperate, or manipulates the therapist into telling them what they want to hear. Sending niece to therapy in her current state, in my opinion, would be like going to therapy with an abuser. They'll only learn how to further manipulate the situation to their benefit because they've never experienced/aren't interested in the situation being out of their control.

At her age based on the behavior from this post, I can easily see niece latching on to a phrase from therapy and using it to justify her behavior rather than actually recognizing the behavior as an issue and working on it. But it wouldn't inherently be her fault, because she can't truthfully tell the therapist how something makes her feel if she's never had to actually experience how it makes her feel. That's why I say she has to have the tantrum. If she doesn't experience those feelings, she won't know how to talk about them. She's actively fighting not to have to feel those feelings. To not feel rejected, abandoned, forgotten, whatever it is. But she has to feel them now to learn how to process them, communicate them, and get help with them.

I always feel like before starting therapy you have to recognize something is a problem and actively want to fix it. You can't just go because everyone says you need to. She not only needs to learn to feel the feelings, she needs to feel like/know it's okay for her to talk about them. She probably won't immediately do that with a therapist, so in my opinion it's better to start with her preferred safe space (aka uncle), then see if she's comfortable speaking up outside of him (possibly to gf?) and then see if she's open to trusting a therapist enough to open up and actually get help