How can a negotiation process end with an unpleasant ending?

Thanks 

I support Romano's answer 

As per my experience negotiations must be ended open and flexible. 

When one party thinks only about their interest and not willing to go for win win situation for other party. 

Negotiation should be win win style, not bias negotiator should think emphatically in order to make sure  healthy and win and win negotiations. 

The negotiator must hear all the parties and respect the views and rely on a variety of solutions and the ability to negotiate and submit proposals and make concessions that it seems to satisfy the parties to negotiate and does not prejudice the work and keep away from controversial issues and focuses on the subject of the negotiations for which he sat for him and sets his goal