Normally I would say start dating a girl that was even hotter and show up to social functions to where she is, and and her hypergamy will kick in and she will want to fuck you.
But my god, you have already screwed up badly at this point, you are taking her out to dinner, and not escalating and now she has finally dumped you to be with her boyfriend, so move on. This is not salvagable, go on the hunt for hotter women, and bang them instead.
But my god, you have already screwed up badly at this point, you are taking her out to dinner, and not escalating and now she has finally dumped you to be with her boyfriend, so move on. This is not salvagable, go on the hunt for hotter women, and bang them instead.