Have you ever started to watch a film (movie) and turned it off because it was too ... dark, miserable, obscure, confusing etc? Your emotional response to a story, whether on film or written, is in the hands of authors and directors. Sadly, you cannot control the emotional response of an audience, but you can consider the level of negativity or positivity you're trying to convey when telling your story.
In the case of the written word, description of setting is one method, as well as the interaction between characters. This is the point at which you need to consider the audience for whom you are writing.
It is at this point that you decide whether you have a calling to be a storyteller or whether you just need to make money and believe that this is a method at which you can be successful. If it is the former, then there will be groups who may not be attracted to your subject or style. (You can't please all of the people all of the time.) If you want to be popular, you may drive yourself to distraction trying to please everyone.
My advice would be to establish your mood and be aware of the need to move on, ensuring that your readers remain engaged and re-energized by a change. One of the most striking examples for me was the musical Les Misérables, and the role of the innkeeper and his wife. The mood of the show is dark, full of pain and pathos, but the directors of the show produced this comic moment, which almost created an audible sigh. They managed to maintain the greedy and heinous nature of the couple later in the show, but for just that moment, there is some light relief. In fact, having read the Victor Hugo novel, there is no such light relief.
Be true to yourself and your style.
God Bless
