My wife had a coworker die by suicide over ten years ago. She really liked and respected him as a person but they were not friends outside of work, and even so, she still tears up when she talks about him. She has gone over and over her last few interactions with him, trying to make sense of it and wondering if she could have known or could have helped him. It weighs heavily on her even though they weren't particularly close, so I can't imagine how the other people in his life feel.