This just sucks.
‘The stimulus may never be known, often is not. Because it is intensely personal it usually cannot be discerned by others, even loved ones. “
Thats not true, many times there are very obvious signs if a person knows what to look for. Many people are not willing to admit their loved one might be thinking of it.
When I was in the Air Force they taught us to ask the person. You won’t generate the idea but it might be the opening they need to ask for help.