One of the rules of negotiation is having real expectations of price. Because of our ongoing conversations, we forget to focus on the core. We start building castles and rope in for the journey together.
When the conversation about price comes, we end up accepting the offer. The sunk cost and all the socializing and projection as a team we have done all this while. It takes a front seat.
Many seasoned negotiators do this to win deals on their terms. They will keep making you run around and again. They will observe you, identify your desperation, and play their cards. In most cases, they win because we are naive and they are seasoned.