California sex laws and restraining orders

My brother who is 18 years old was having a relationship with a 17 year old girl. He just recently turned 18 and they have had this relationship as minors for about 8 months. Her parents approved of this relationship up until recently and have forbidden them to see each other. Recently my brother went over there to see his girlfriend and snuck in her window, they were not actually caught but her parents noticed footprints on the window and then decided they were going to pursue a restraining order against my brother. Can they do this? He has never threatened her in anyway or harmed her and there has been no incident actually reported to the police. However, a police officer called my brother many days after her parents found the footprints and told him that the parents had called and had decided to not to press charges and this officer proceeded to tell my brother of potential consequences if another incident happened. However, there was no incident reported on file as we know. They have no actual proof that my brother was there except for what they assume and he did not break and enter as the afore mentioned girl let him in willingly. Also this police officer who called did not specifically say that the parents had filed a complaint. However, now they want to file a restraining order. Again, can they do this if there is no viable reason or report to verify the filing of this? My brother has a clean record and doesn't even have a juvenile record and has never been in trouble with the law. They are also threatening my brother to leave town or they will continue to pursue legal action. Do we have any recourse, I mean isn't that harrasement? Could we take them to Civil Court on harrasment charges for them trying to chase him out of his own town by continually threatening him with the law.
Also in California can my brother be charged with statutory rape as she is 17 and he is 18 now even if they consesually had sex before? Also if they can file statutory rape charges don't they have to prove somehow that they actually had a sexual relationship? If they both deny it can the charges go through?
Also if a restraining order is placed on my brother, when she turns 18 and moves out of her parents house does the order become void? Or do her parents have to lift it? Thank you for your advice on this matter.

[randalljd]

See http://www.ageofconsent.com and /or http://www.avert.org/aofconsent.htm and confirm with your local police dept and/or District Attorney's office.