The 28-year-old actress-and-model was awarded a temporary restraining order by a court last month but she has reportedly had difficulty in serving him the order and so is heading to see a judge.
At the court hearing, sources say Karrueche is planning to tell the law official how she fears for her life, TMZ reports.
It comes after Karrueche issued a sworn statement to the court last month where she claimed he ''told a few people that he was going to kill her''. She also alleged that Chris told the people he was going to ''take her out'' and ''shoot her'' if they couldn't get back together.
Karrueche also alleges that Chris, 27, had ''punched her in her stomach twice [and] pushed her down the stairs'' several years ago.
Meanwhile, Chris had previously appeared to comment on the claims made by Karrueche in a video posted to his Instagram account.
In the video posted online, he said: ''Make sure y'all don't be listening to all this bulls**t man. I don't know what the f**k they're talking about. Don't believe all that bulls**t, bro.''
And Chris previously described himself as a ''stalker'' boyfriend.
He said in a clip posted to his own account on the photo sharing site: ''Ladies, y'all be complaining about n***as being, like, stalkers and in love with y'all, kinda crazy and s**t and you get tired of it. Well, guess what?
''I'm one of them n***as! If I love you, b***h, ain't nobody gonna have you. I'm gonna make you miserable. I'm going to chase that n***a out and I'm gonna chase yo ass around, and it's done.''
What's new in the music world this week?
'Sounds of Silence' was released on this day (January 17th) in 1966.
Listen to Alex Bayly performing 'Animal'.
Two weeks ahead of Independent Venue Week, Dry Cleaning made 'Britain's Best Small Venue 2015' (NME) the second port of call on their 2020 tour.
'Leave Home' was released on this day (January 10th) in 1977.
For their last gig of the year, The Libertines came back to their adopted hometown of Margate to finish off their latest tour.
Celebrating the birthday of David Bowie with his most legendary songs.