Unless you can find the coroner's report or newspaper articles you might never know the why, My paternal grandmother took her own life in 1932, I have a copy of the coroner's report a copy of the doctor's report who was called in to determine her cause of death & newspaper articles so I have a good idea of why she did it, to me the most important was she was determined to be of unsound mind at the time, I don't know for sure but I think this is the reason she was able to buried in consecrated ground.