Once the book has been trimmed down, you have to make sure that all the details add up. No magic cigarettes that get stubbed out on page nine and are suddenly back in the hero's mouth on page 10. No mysterious brandy glasses appearing in the hands of characters who had not been drinking a moment ago. In one abridgement, the hero was shuffling papers on an airplane, then put the documents in his briefcase and gunned the engine of his rental car. The book has a physical world, and the abridgement has to preserve it.
Relationships are as hard to manage in an abridgement as they are in real life.
She brings out his gentler nature. He restores her ability to trust. Abridgers have no time for that. Kiss and move on. We've got a schedule to keep.