The phrase "tidy endings" means when things are neatly resolved or wrapped up in a neat and organized way. It refers to situations where all loose ends are tied up and there are no loose or messy parts leftover. Full definition
The relatively tidy ending also feels slightly lazy after a series of more challenging plot twists. (nme.com)
A too - tidy ending notwithstanding, this is an exceptional character study of a young woman and her hospital mates who struggle with demons so severe that only their bodies can confess. (booklistonline.com)
Do not, though, expect too tidy an ending. (haberarts.com)