Sorry no Buddhism perspective here either, but just my own thoughts.
It doesn't matter how hard you want it, or how much you try to change it, you can never change someone's feelings or behavior in this situation. Experience has told me the only chance you have to change it is to walk away. While you are still there letting them treat you that way they will continue. If you say "no, enough is enough" and walk away then, perhaps they might re-think their attitude/position. When they are ready they'll find you. It's so hard when you love someone unconditionally and they don't reciprocate in the same way.