I'm so sorry to hear about your nephew's death.
I wish I knew the right words to say to make you feel better, but I don't.
People who commit suicide seem to have just as many rationales for their act as there are people who love them who worry that it might have been something they did or said to push them "over the edge".
There tend to be several "themes" to suicides:
Revenge: This is the "You'll Be Sorry When I'm Gone" kind of suicide of a jilted lover or teenager who's bucking parental authority or house rules.
Fear of being a burden: This type of suicide occurs usually when there's a serious illness involved, including cancer, depression, alzheimer's, etc. The person fears losing "themselves" to the disease, and having the people around them have to be burdened with their care.
Escape: The person feels their life is worthless and their problems are insurmountable. For instance, a bankruptcy, divorce, failed relationships, losing their job (shame). We had a suicide last year at the hospital where I work of a young man in his final year of residency, who was being sponsored by the government of Saudi Arabia. He failed his final rotation and was given a poor evaluation, and expressed fears about losing his sponsorship and having to return home in disgrace. Later that morning, he jumped from the 15th storey of the residence building on hospital grounds. I think this also may be a factor in the Bryant suicide, that he was pushed to his limits by the consequences that JW shunning brought to him and his family.
Manipulation: Some people attempt suicide without actually intending to cause fatal injuries to themselves. They feel neglected by their loved ones, or are trying to manipulate people into catering to their wishes to keep them from carrying out their threats.
Then there are accidental suicides. Kids goofing around with ropes hung from trees branches playing Tarzan... that happened here over the weekend.... just dreadful
Anyway, that's all I can think of off the top of my head from my psychiatry studies. I'll look at my textbooks later after the children are asleep and let you know if I find anything else.
Again, I'm very sorry for your loss. Wish I was close enough to give you a big hug!
Love, Scully