How do I win this girl over?

There is really no way to win her over - she’s obviously confused. She basically cheated on her boyfriend with you, then told you she wanted a friendship, then cheated on her boyfriend again…that’s ridiculous. Honestly, she is unhappy with her boyfriend but is not ready to leave him for anyone else. She was intrigued by the romanticism you displayed. However - you’re not her first choice. She’s already playing games with you and being indecisive about what she wants. That should be enough to reconsider the situation. If she is doing this to her boyfriend, she will most likely do it to you. I understand your situation though. Pressuring her and chasing her will not work. She will enjoy the attention and delay the decision making process for as long as she can. Even if she does break it off with him, she will not cut all ties with him immediately. If you really want to win her over - then I would suggest the following. Continue to speak to her…act gentlemanly…be nice…BUT back off. No romantic ploys. You’ve done your part. Do not chase her…This will keep her wondering. Make her work to get you. Do not kiss her. Let ker kiss you. Be the first to end the conversation…etc. I know it will be hard, but it will work to your advantage. This may not guarantee a drama free relationship, but she’ll definitely want you more (as you’re already experiencing drama). Good luck!