To your point, one of my closest friends killed himself almost 15 years ago. He lived next door to another one of our close friends. He killed himself on Monday morning after Super Bowl. He had attended a Super Bowl party at our friend’s, his next door neighbor’s, house that night. I spoke to him on the phone that night. We laughed, we talked about a trip we were planning with our group of friends and we BS’d about the game. No sense at all from me or anyone that attended the Super Bowl party that was anything was amiss. The next morning he was supposed to meet his mom, who also lived nearby, for lunch. Instead he walked out into his backyard, stuck a gun in his mouth and pulled the trigger. Turns out that he had bought the gun several weeks prior so he had likely been experiencing suicidal ideations for a period of time and none of his friends or family members had any clue. Mental illness can sometimes be invisible to the people closest to the victim.