I notice that a lot of art journals only seem to cover the happy parts of life, as if only the pretty parts are deserving of a page.
Ignoring the crappy hard parts of life isn't the best way to deal with the garbage. Disappointment, sadness, death, and our distress all deserve to be explored and figured out in the pages of our art journals.
My art journal is a place for me to work out my thoughts and ideas, exorcise the demons if I need them gone. It's a place to explore and even fail.
I've got some dark not so happy stuff in my journals, and that's just the place to shut it away.