this is kind of a half-baked thought but there's also something to be said for the idea that Rumi doesn't, like... reward Jinu's manipulations. She mainly rewards him being vulnerable.
Like, the most obvious manipulation in their first rooftop meeting is the "You know you can tell me. I'll understand. I'm the only one who can," but I don't see a lot of people pointing out that Rumi responds to that by putting her sword back up. Immediate suspicion and distrust, where she had let her guard down a bit before. She doesn't fall for it, even though she's in a situation where it'd be understandable if she did.
Instead, the thing that she softens for is when Jinu starts opening up to her. And obviously he's changed pieces of the story, but the baseline he tells her here is true: his family was poor and struggling, Jinu made a deal with Gwi-Ma to get out of it, now he's Gwi-Ma's prisoner and is haunted by the shame of leaving his family.
And then later, at the fansign, when he tells her "you can't even talk about your patterns," she responds by stomping on his foot. And before that she was mainly ignoring him. She only softens and acts more friendly to him when he actually shows a bit of vulnerability, looking at the picture the little girl made.
I don't feel like I can talk much about the next two times they meet, mainly because... Jinu's just not trying to manipulate her at all at that point. So there's not much of her rebuffing him. But of course she's very welcoming and encouraging of him being vulnerable there as well.
And then later, after the Idol Awards? She doesn't let him get away with it either. When he says "I just needed you to trust me," she immediately responds by basically saying, "no, fuck that, I know that's a lie, come back here and be real with me."
I don't know. I think there's something to be said there for... the amount of control Rumi had. Jinu tries to manipulate her, but she pretty easily dodges whenever he tries to drag her into some toxic, dependent mentality (with the exception being the blind spot that they both already shared, which is the idea that demons deserve to suffer), and stays focused on the pieces of actual information that he gives her. That's... I mean, that's not nothing, you know? When we're talking about their dynamic.