Books that the character commits suicide and also brings interesting reflexions as this fragment “The human race is a monotonous affair. Most people spend the greatest part of their time working in order to live, and what little freedom remains so fills them with fear that they seek out any and every means to be rid of it.”
It can be in french, english, german literature as the main languages I want to learn but also other languages if I can find a english translation...
Rayuela - Julio Cortazar. In there the main character try to commit suicide and the plot is similar in some way to Werther.
Crime and Punishment - Dostoyevsky. The main character doesn't commit suicide, but the plot and the characters a very dense.
I would recommend you a book written by a Japanese author, I think it fits pretty much what you are looking for.
The English title is "No Longer Human" by Osamu Dazai
There is also a German translation, the title in German is "Gezeichnet"