Bad reputation with him?

I have a bad reputation at school for "backstabbing" my friends which is not at all the true story of my friendship. The problem is... the guy I really like seems to follow along with this reputation and really believes that I'm like that. Is there any way to get him to see that I'm NOT like that? I've tried showing it to him by being friendly, but he seems to scared to be my friend for fear that I will do the same to him.