Ah. Solutions. I’m going to be very blunt.
Is she a puzzle, a complicated problem to “solve”? If only you could figure out the right buttons to push! The right words to fit into the right locks!
Or is she a human being who made her own choices?
The true strength and beauty of any relationship lies in that it is built upon the free choices of both (or X number, to be inclusive of the polyamory folks) people involved in it. Those choices are made each day, consciously or unconsciously, explicitly or implicitly, but they are made. When they are freely chosen and move in measure together, that is a healthy, functional relationship. The more out of tune those choices move, the more shaky the relationship is. Past a certain point of moving out of measure, the relationship is no more.
She made her choices. By not “giving up”, by wanting to “solve” her choice, you–very bluntly–show contempt for it.
Stop. Sit still. Breathe silently. All things are finite, all things impermanent, all things come to their end. Give thanks for the time you had, do so honestly.
And then walk away, because if you don’t let this go, if you persist in wanting to “solve” another person’s choices, the only result you’re going to achieve is bringing more suffering into the world. By my reckoning, that’s wrong no matter which way you slice it. But I think you’ll end up doing so anyway, which is a shame.
What’s worse, it’s a pattern you’ll probably repeat–people tend to be cyclical critters in their actions. My best hopes you learn what the pattern has to teach you without it needing to go through too many iterations before you get it.