EmberJS: how to remove records with many-to-many relationship

I stumbled across an issue when I tried to remove a record whose model is in many-to-many relationship to another.

I have Book:

App.Book = DS.Model.extend({
    title: DS.attr('string'),
    isbn: DS.attr('string'),
    category: DS.attr('string'),
    publishDate: DS.attr('date'),
    authors: DS.hasMany('author', {inverse: 'books'})
});

as well as Author:

App.Author = DS.Model.extend({
    firstName: DS.attr('string'),
    lastName: DS.attr('string'),
    birthDate: DS.attr('date'),
    books: DS.hasMany('book', {async: true, inverse: 'authors'})
});

I am removing books like this:

actions: {
    delete: function (book) {
        var authors = book.get('authors')
        authors.forEach(function(author) {
            var books = author.get('books')
            books.forEach(function(book){
                console.log(book.toJSON());
            })
            books.removeObject(book);
            //books.save doesn't work
        })
        book.destroyRecord();
        this.transitionToRoute('books.index');
    },

and it correctly removes this book, with DELETE request to backing REST server, but there are no PUT requests for all those authors which had this book in their 'books' collection. When I change view to authors and go back to books one dummy book is created with id of the one I previously removed and 'authors' set to old author as well, other properties are undefined.

How do I correctly remove books so that authors are updated as well?