Apologies for the late contribution but I don't often come into the Family Room. Someone close to me is going through a milder version of this with her (female) partner. It's good advice to document everything as it's easy to let yourself forget once it's over and it's helpful to have a record, whatever he decides to do. If he won't, could you start documenting for him based on what he reports and what you see? I'm not an expert but if it's an established pattern that has escalated from an already turbulent relationships then it's not going to get better on its own. It sounds as though his partner is unstable (I mean that non-judgementally) and needs help, which may mean she isn't 100% responsible for her behaviour right now. Understanding that may help him to take action as he may have to be the sole adult in the family for a while. I wonder if it would help to have a chat with him and get him to clarify what he wants? Whether he wants the relationship to continue or not, I would suggest you encourage him to call the police when she attacks him physically. That may be the shock she needs to admit she needs help, but horrible for him to do as it feels incredibly disloyal and he may fear her reaction. Perhaps he could also talk to her doctor about his concerns for her and the child, or could he talk to her parents/family? The child's safety comes first and obviously it's not great for them to witness what's going on - including longer term as it will inform their idea of how relationships work. If they split up, a judge will assume 50/50 custody unless there's a good reason not to, and it sounds as though he may have a case for sole custody if he will document the evidence.