Can't have sex??

I'm in a relationship with a guy I love and who loves me.. we've been going out for about 5 months now, but we haven't sealed the deal.. and it's all my fault. Every time he tries to or an opportunity comes up I always flake. I don't know what it is but I'm scared to (I have had sex before..), I don't know why and it's starting to effect my relationship. I was in an abusive relationship before I met this guy I'm dating now.. but I don't know if that has anything to do with it. This guy I'm with now is a virgin, but I really love him and I'm trying for him. Anyone have the same problem/ know what I should try??