I think Free is perfect for what it says about Rumi and Jinu's relationship. Like, they are both hiding things from each other and from others in their life (at least Rumi is because Jinu doesn't have anyone). But even despite the secrets they still have, the impact they've had on each other is real. Jinu may not have told Rumi the truth about his past, but the positive impact of her acceptance on him is still real. The step they've helped each other take towards healing is still real, the hope they've helped each other find is still real.
I think it's crucial that even though they sing about running away from their patterns, etc., they don't actually do that in the song. Their patterns are more visible than ever, and they even hold hands like that. That's the important part of the song, I think, that even though they haven't completely been able to get rid of the perspective that they have to escape themselves, they still found the acceptance that they didn't know they needed in each other.
They sing about how they want to escape at the same time they're singing about how the other saw them and accepted them and how much that meant to them. I feel like that's part of the bittersweetness of the song, that even though what they need is right in front of them, they can't even see it. And it's realistic! It's not that easy to change something you've believed for years and years (centuries in Jinu's case lmao) but they still got what they needed from each other, even if they don't understand what it means.
Neither Rumi or Jinu could "change" because of each other, but they wouldn't have been able to "change" without each other either. Neither of them knew what they were doing, but they managed to have a positive impact on each other anyway, and that's the duality of the song. Two broken people finding each other, and it doesn't magically fix both of them, but it helps them find hope.
They didn't magically change each other's mind overnight, but their connection had a positive impact on both of them, and even if they couldn't see it yet, they gave each other what they truly needed in that moment. Acceptance, understanding. It paves the way for them to heal even if they are still trapped in their flawed ways. They don't fix each other, but they can be broken together.