Crazy romantic things to do for gfs birthday?

My girlfriend is turning 14 and she seems to not really like me as much as she used to and we seem to be falling apart, but I want to do something for her birthday that will prove my love for her. I already got her an awesome gift and I'm thinking about hanging up signs around town that say Happy Birthday to her. Any other ideas?? Please, any would help. I'm kinda shy but im at point of trying anything lol.