I read a submission once that was very well written, if a bit bleak. I asked to see the whole manuscript, and the overall quality was excellent, but there was a problem. Not a single one of her characters survived.
Now I'm as fond of a dark outlook as the next moderately gloomy person, but there are limits. I also know that unrelenting fictional misery is very hard to sell to a publisher. (Note, I say 'fictional' - there has been a well-publicised trend for Misery Memoirs about horrendously abused children, but that seems to be waning).
I wrote to the author explaining that I loved her style, but that the plot was too dark, what did she want to do about it? She wrote back immediately - saying she had another manuscript in her drawer, and this one was much more cheerful, did I want to see it?
I settled down to read it, feeling optimistic. It was more cheerful. Marginally. The two main characters survived the ensuing blood-bath, but they did end the novel having agreed on a suicide pact.
There is a thin line between writing for yourself, and writing for publication. No-one would recommend you try and write simply to get published, but there are commercial realities that the aspiring author needs to be aware of. In this case, the author preferred to continue with the body count, than try to get published.
What would you have done in her position?
(Editorial Consultant)
I would make my best to figure out a very good reason to the suicide pact which makes the readers be 100% agreed with their decision.
Novels don't have to have happy endings, and good novels raise more questions than solutions. For example Junk by Melvin Burgess ( which won a carnegie medal). But I like to think that the trend nowadays, is for novels that have dark or sad endings to at least end with a hopeful outlook.Do aspiring writers want a fanbase or to write for themselves? I forget which successful author it was I saw being interviewed. But when she was asked, ' Why do your novels always have a hopeful future, or happy ending?' She replied, 'It's what my readers want.'
I think I would take on-board the comments and take a second look at my ms. It really depends whether it is gratuitous or enhances the story in some way... like Freya above says, the story/journey has to be worth the bloodbath ending.