What propels suicide?

I was on the 86th street subway station in brooklyn, the 3rd n last leg of my daily morn commute. The R train was not running either direction...the pa intoned periodically that service was delayed due to an injured passenger on the 59th street station. Initial reports on local media online indicated a woman jumped inyo the tracks to retrieve a cell phone which fell...n subsequently fatally hit by an oncoming train. Power was then shut off delaying trains Despite constant posters warning do not jump on the tracks to retrieve anything fallen...i wanted to both strangle n hug n comfort her(metaphorically speaking). Later reports stated that investigators felt it was suicide. What torment possessed this woman? She is amongst the stars now...from which all of us were made from.