Intentional. If you weren’t sure where you partner was but you did know someone was in the loo, why shoot through a closed door when it is likely she could be in there? He said he was feeling vulnerable because he didn’t have his legs on, but he was armed and he had no idea if the person in the loo was armed. You don’t just shoot through a closed door unless you are intent on killing someone. They apparently had a row, she hid in the loo to get away from him and he shot her.