Most Helpful Guy
Lot depends on the country you are from but I presume what you are looking for is a restraining order where if he breaks it, he can be arrested. I think what the police are saying is restraining orders can't be given without evidence of threatening behaviour (filed reports) . I presume they are afraid of false claims of behaviour against innocent people by other people who hold grudges. Its a catch 22 - You can't prove the behaviour until you have suffered it and filed reports.
Most Helpful Girl
Like everyone else suggested, get a restraining order and keep documents of everything he does to you. The way the law works is they have to catch the person in the act. This basically takes out all the possibilities of you lying about the situation and any way it could just be a misunderstanding.
For example, a guy tried to break into my apartment while I was home. He never entered my apartment, & I was able to see who he was through the peep whole. From there I took pictures of the guy, what car he got into, & this license plate number. There was even marks on the door where he was trying to get in. When the cop arrived, this was no good, because the guy never entered into my apartment and stole anything. The cop further explains he could just be an ex boyfriend & I could be making all this up just to get him in trouble.
Another incident I had, was a coworker tried to bag her car into me, on the side of the road at work. When I spoke with an officer, he told me that since I wasn't harmed & the area I has standing in could be used as a parking spot there isn't anything they could do about it.
I guess since so many people have "cried wolf" & caused unnecessary arrests cops have chosen to stay out of it until something serious actually happens.