She didn't "screw up", she made a choice that was not you. You may think this was a bad choice but it was hers to make. If she was still interested in you she would have kept seeing you and not started seeing someone else, it's as simple as that. One thing that strikes me is you seem to talk about women as though they can be manipulated and tweaked into making relationship choices, as though it's you versus other guys and the women are the chess pieces and you are trying to decide what your next move and counter move with the other guys should be. You can't actually tweak a situation in such a way that it produces your desired outcome. Women make their own decisions.