When faced with life's trials, some people take "shortcuts" by suicide. Even though suicide is not a solution and not a shortcut, even suicide is a very big sin in Islam.

people who commit suicide actually think short and shallow by assuming that if he dies then everything ends. It is precisely the life after death is the real life that is more eternal more severe. If someone who does not have enough provisions for his afterlife then he ends his life in the world with a big sin, which is suicide, then he leaves a much smaller problem in the world (when compared to problems in the afterlife), then faces a bigger problem and heavier in the afterlife.

I hope this answer is useful.