Is it possible to get a restraining over for this reason?

My friend is freaking out. Anyways this is the story. My friend has been dating her boyfriend for a little over a year now. She is now 17 years old and he is 20 years old. Her parents never really liked him and always asked I or one of her friends to try to convince her to break up with him due to the fact that they always are having problems and he is a very emotional person. I have been there once last summer and he has got mad and slammed the door in her own house. I really don't hang with them together much so I don't know what really goes on but what I do know is they are happily in love with each other. From what I have seen in the past was when he would get emotional, she would give in making both of them needy people. I guess you could say they are good for each other. Anyways, I do know that the boyfriend of my friend never physically abused her in any way and she chooses to be in this relationship. The only reason why I am freaked out a little is when she says if she ever broke up with him, he would kill himself. I know he has alot of issues but I feel that he wouldnt do that because they broke up once before, and she does llove him and chooses to be with him on her own will. Both of them have their own issues, and they are good for each other. Based on these facts, her father wants to put a restraining order on her boyfriend because he called the cops twice to check up on her because her father has hit her.( Her father got angry at her and hit her in the hand, and she claimed today that it was swollen last night. Her hand was fine today at school when I saw it but that is what she tells me. According to her, her father has hit her by punching her in the past or whatever because she has done something wrong. This could be the reasons why she has done things like cut herself, or she has attempted sucicide when she was younger. But then again, I do know she has lied to me about somethings so it is hard sometimes to distinguish from the truth or a lie if her dad has done everything to her. However, there must be some truth because there is no reason for her to make those things up.) Anyways, since her father wants to put a restraining order on her boyfriend, does he have anything he can use towards the restraining order? I don't think it is possible for her boyfriend to get a restraining order for calling the cops on her dad. Also, she does have sex with him but I have heard that it is perfectly legal for them to have sex because she is 17 and he is 20. It also isnt possible for her father to put a restraining over on her boyfriend because she is a minor living under the parent's roof, am I correct? I am trying to reassure her that her dad will in fact lose the case