It seems only fair (from my point of view, of course), that if I am willing to committ significant time and some expense to a buyer, they not flippantly waltz off to another agent.
That said, any time a client of mine is unhappy with my services, I will let them out of whatever contract. In this case I would keep the list of homes that I showed them, to which the 90 days applies (buy one of those homes within 90 days from either the end of the contract or the date I agreed to discontinue it) and you still owe me a commission.
I've never had a client ask to be released, and I do not have a buyer-broker agreement in every case.
Now most agents probably wouldn't enforce it but I know some would. Except for some specific markets most top producing agents I know don't use them at all.
In other markets where there is a lot of jumping back and forth between agents then the practice is normal. A realtor doesn't get paid even if they take you through the entire process and get you into contract, if your deal doesn't close.
If you have reservations you need to find another realtor whom you know is the right one for you instead of wondering whether or not the fit works.
I work under contract with all my buyers and I always tell them they can "fire me" if I do not meet their standards! So far....so good! Please speak to your buyer agent and get the terms clear between you before you start working .
Dave's approach is a good one. You can always speak to a real estate attorney if there is a big issue but this will cost you some money.
I have a friend who signed one such agreement without reading it carefully. The agent put down one year's representation. When she wanted to change agents she was threatened that she is liable for commission to that agent even if she used another agent to find the property she buys.
So pay close attention to the timelines and the paragraphs relating to Broker compensation and buyer obligation to pay compensation. Additionally, specify what property or type of property you are obligating with this agreement. Some buyers may use one agent for residential property in a specific city, and use another for a different city.
You will be obligated to work with that Agent exclusively for the duration of the Buyers Agreement, unless the Broker agrees to release you from the contract. I suggest you keep the Agreement capped at 1 month. If at any point during that 1 month you find yourself unhappy with the Agents services you should approach the Broker and ask to be released from the Agreement. Make sure that you get the cancellation in writting. Good luck!