How can i keep a girl interested?

2 years and 7 months is a long time and maybe she wants to move on but ur feelings are holding her back. so i suggest u ease up.ask her if you are holding her back from happiness if you are then just let her go. this may hurt you now but she wil be so thankful of you and it will make u both better because neither one of you will be stuck in a relationship. If you dont let her go now she will eventually dump you and you will feel worse when u gt dumped.