We don't know for a fact that this assault occurred. We don't know if the boy friend was an ex or just a boyfriend. In the speculation game which we could play, we don't know who was, and was NOT unwelcome at the new apartment. There is a flip side to this that must be at least considered.
Did an assault by the male occur? Unconfirmed
Was he an ex or boyfriend? Unknown, unstated, iirc.
Males father and Brenna's father are both speaking with police, according to Brenna's mother. What were those discussions.
According to Brenna mom, Brenna has been filed as a missing person, but it is unconfirmed by any authorities, to the best of my knowledge.
I could provide a lot of conjecture as to the reality of the situation from 2 different angles. However, using a tad of critical thinking, from my views, a single point source of information being only Brenna's mother, creates more questions than answers at this point.