Only if they’re aware, though. Not specifically for Nicola’s situation as I’m not comfortable speculating about her MH situation, but in general if someone is functioning on the surface and there are no obvious outward signs, then the person reaches breaking point / crisis, suicide comes as a shock to their loved ones who had no idea what was going on and healthcare professionals weren't ever involved because there were no outward signs of an issue.There are some signs that mental health professionals use to assess the likelihood of somebody acting on suicidal thoughts.
(not disagreeing with you BTW, but realised it might sound like that! Am totally agreeing, just mean professionals can only judge if they know)