It would have been better if you knew exactly what you wanted in a partner before you even started dating her. So I will recommend you two workings instead of one, and this is from my own knowledge and what I have read from the ToZ, but are you really sure you are not in love with her anymore? If you are, then you can use the rune ISA, vibrate it for 11 times, or any multiplications of 11, and do this for forty days. Use the affirmation: " In positive ways for me, X (your gf's name) is no longer interested in me, romantically or sexually, and wishes to move on, permanently" x9 times, as nine is the number of endings.
As for the secind working, you need to be someone who meditates regularly, does cleaning, protection etc., but basically you want to gain insight on what it is you truly want (do it even if you think you know, it will still be helpful): SOWILOx16, ANSUZx8, with the affirmation: "I am now completely aware of my own true sexual and romantic tastes and needs, now and forever."x8, as eight is a number of permanence.