As much as i dont agree with your motivations i will give u advice on this.
If you want to keep her around, bind her to you
If you want her to love you, influence her mind to keep thinking positively of you and then do a love spell
If you want her to want *** with you, then create in her lust for you and use the fire element in your working.
You can do all 3, one of them or 2 of them, whatever.
If you want her to only have you, permanently, bind her to never have another partner other than you.
Please keep in mind that love spells dont really create “real” love, although it may feel like it. If you want to go the longer and more strategic route, you can do the one above this paragraph and then work on her mind long-term.
Bind her to meet people who will tell her to forgive you repeatedly,
Influence her mind to think positively of you,
Influence her mind to dwell on you (domination magick)
Influence her heart to lust for you
Then when you meet up with her again, be kind and apologize for anything you did and say that you missed her. Go from there and let love be kindled again naturally.
Magick isnt always a one-ritual and done thing. Sometimes you have to strategically plan the rituals and spells to get the best out of them. Sew the seeds, let them grow, and harvest the rewards.
If you do this, please treat her well and dont use her.
Id also suggest you do things to improve yourself while all this is stewing in her so she sees you as a better candidate for dating.
if you want to conjure a demon for it, Prince Sitri is pretty good with Lust and Duchess Gremory is good for procuring love.