My boyfriend has a child from his previous relationship...?

they have been broken up for almost two years now, and she's still haring him! she show;s up at his job and attacks him calls his phone and even threaten to take his daughter away, her problem is me and i never even seen the girl, she claims that her daughter doesn't like me which is a complete lie, she's 4 and as precious as could be. we've been together for almost a year and this is the 3rd time she attacked him, if he gets a restraining order will he be able to still see his daughter? she needs to stop popping up at his job and home unannounced trying to fight hi...what can he do? by the way they were never married just had a kid..