The success of negotiation is limited by a number of factors. One of these is the presence of better alternatives to the expected negotiated agreement. In order to know whether or not to accept a proposed settlement obtained through negotiation, you must know whether or not you can get a better outcome in some other way.
Good negotiators know when their opponent is desperate for an agreement.
When that occurs, they will demand much more, knowing their opponent will have to give in. If the opponent apparently has many options outside of negotiation, however, they are likely to get many more concessions, in an effort to keep them at the negotiating table. Even when disputants do not have good options outside of negotiations, they often think they do. Yet, perceptions are all that matter. If a disputant thinks that he or she has a better option, she will, most likely, pursue that option, even if it is not as good as she thinks it is.