Who do you want to forget, your girlfriend/partner? It's quite difficult to break such bond (assuming it's about relationship) if you actually love her. If the attachment is due lust, you empower yourself to get detached, by fasting, praying, reading/listening to Word of GOD (especially Book of Proverbs:
https://www.youtube.com/watch?v=liPJFT-5Bug&list=PLIxhnx0kb33ORn8RQgHH54rdJMmqaRfmd&index=20 ) living a healthy lifestyle etc
People can be free from lust once they have been freed from an unseen system of bondage/slavery which they were born into.
Only by believing and obeying the CREATOR's Word can anyone be freed.You can go through other Books after listening to the Proverbs....
If you genuinely love the partner and she doesn't love back, just let her go and be happy. Perhaps this behavior could convince her you truely care. In True love, it's about the other person before yourself. you could try and get her to reciprocate the love by treating you as brother... And no inappropriate touching or feelings. Just building up each with good things of life.
If you want to totally forget, I don't think it's necessary if she didn't deliberately do you wrong... (unless maybe she did you wrong and don't care she did you wrong). We don't forget people we truely love, or do we?