Untidy endings

It's a good idea to try and tie up all loose endings when finishing your novel.

Readers want to know what happened to your characters, how mysteries were solved, and the outcome of dramas. They want to know this not only for the main plot, but for the b, c, and d plot as well.

Tying up all loose ends helps leave your readers satisfied that you've covered all your bases.

That doesn't mean that you have to tie up all your endings nicely in beautiful bows, however.

Some endings are going to be messy. Some are going to be unhappy. Some are going to lead to new beginnings for characters.

You don't need to find a happily ever after for all your characters, but you might want to think of making sure that your readers know where they end up to create the feeling that the ending of your story truly ends the story you created.