Sometimes it is not what you did wrong, there are some buyers will just listen to other's opinion. Especially when a builder tells them they don't need an agent, the builder can use the agent's commission as a discount for them. To us, it doesn't cost a buyer one thing to use our service, but when someone told them they can get a house cheaper without using us, what do you think they will do. I had 2 experiences before, one of them actually told me they are definitely use me as their agent, a month later, they used a builder without letting me know. Don't take it personal, sometimes we can't please everybody, and there are some buyers not loyal to anybody. We just have to move on and focus on next project, don't waste your energy to keep thinking what went wrong. I know exactly how you feel, that does make us mad, but you have done everything a good agent should do, there will be always another buyer.