i think grief, sexual abuse, financial problems, remorse, rejection, relationship breakup and unemployment are linked to a higher risk of suicidal ideation
It can be inferred, from all the causes of the suicidal thoughts you mentioned, that the cause of suicidal thoughts arises from depression, deep depression which is self-contained. Depression, unhappy, was tired of all the problems they had, and eventually decided to commit suicide so that all the problems would not be felt again.