I think it's, as you said, a "having the cake and eating it too" situation.
She has feelings
to a degree, and doesn't respect your feelings enough to hold back on expressing those in the messy way she has, but there's also a withholding and micro-managing of her responsibility towards you and the outcome by saying "maybe not" because she's probably sure she's already made up her mind and is managing down your expectations of her while keeping you in the placeholder position as a security measure... we've got to look at the withholding aspect of this, because what that means
at best is: "I want you...
but not quite enough"
It's the unsaid "but" we need to be paying attention to with mixed messages. It likely means they've identified (a) reason/s why you're not enough of something or you're too much of something, whatever it is, it's that they need more/less of something and have decided they can't have or don't want that with you, and they've decided they want that more than they want to be with you, or that being with you is too painful because it means giving up the fantasy of finding it elsewhere. (ahhh, "The One")
She might be using you as an open diary that helps her get over the relationship - does that make sense?
By being available and allowing all that open expression without enforcing our own boundaries, we're nursing someone through the break up because they know the door of a relationship is still open which actually reminds them they still don't want the option which potentially motivates their moving on while we stay stuck in that placeholder position hoping for them to change their mind. This is why I think the no contact rule is really helpful.
She might very well just be testing to see if the door stays open as a security measure for
if she decides she wants it, or as an ego boost.
This is what I think my ex tried to do with me... I went 20 days N/C after the break, he text me during that time, and then I initiated a closure conversation where I was compassionate and said we both deserve to be happy and that I'm glad about all of this but that I can't be friends, because that's not what we were to me. I am now back to N/C, while he still wanted contact and has tried to still get me to call him and trying to make conversation (reading the books I like/learning about things I like/talking about what he's learned about attachment theory)... it's clear he misses me somewhat. But the important thing is that he doesn't want to be with me
enough, which is how he let me go in the first place. It would be more likely that he wants
the option he had but now realises the window of opportunity has closed on him. He wants control over something he used to have control over. At best, he wants
an idea of me caused by missing me during N/C or seeing me conducting myself well and independently, or he wants friendship so he can have our connection on his terms without having any real responsibility towards me or my feelings towards him, and have the great things about me while he finds someone else who doesn't have the traits he loved in me, and gets the best of both worlds.
It's about respecting yourself enough that you won't be someone else's pacifier while they deal with being single again - it's maybe N/C is one of the most effective ways you can make them realise what that greatness was now they are devoid of that in their life or the next person doesn't fulfil the needs in her that you did, and she might remember that and realise through that in what ways she undervalued you at the time... or not... in which case, good riddance it did end, I suppose.
I really do think in this position the best response is to take away all hope for them being
able to come back - you get your power back, and either make them realise what they lost or lose someone who didn't deserve to have you in the first place. If we show them that we really don't need them and that we're happy things are over but that we're polite with them but try to minimise the contact - I think they will really see our worth in a different way. It's worked for me... No, he hasn't asked for me back, but the last I know he was asking for me to call him sometime and messaging to make conversation and I haven't even opened the messages. I went to a houseparty instead. He had the power, and now I have the power. It isn't really about power though, it's about thinking yeah, I respect me enough that I won't be your fallback and I will gladly remove myself as an option, for someone who deserves me more.