Keep the disturbing party in sight, in any area that has been subject to a protective sweep and where their hands are apt to be in plain view.
If the disturbing party wishes to leave and is not subject to further detention or arrest, tell him or her that's fine, but not to return to the location while you're there, as they may avail themselves a weapon in the interim.
Personal Experience
I hate domestics, and was wounded while responding to one when an idiot ambushed another deputy and myself with an AK47. Perhaps predictably, the girlfriend we saved—the one who, along with her family, was the object of the suspect's murderous rage in the first place—pissed backward when it came time to go to court and testified on his behalf (he was still sentenced to 160 years).
Personally, I believe that the first time any person becomes a victim of domestic violence, law enforcement officers should do everything in their power to insulate them from any further attack. But the moment they go back to the abusive son of a bitch, then we should be able to wash our hands of them. Professionally we don't have that discretion: We are expected to continually run interference on behalf of these Darwin Award aspirants.