A purchase contract is not between three entities, it is only between two, the buyer and the seller. Execution of the contract is dependent upon the seller's acceptance of the buyer's terms. In consideration of the acceptance, your agent should advise the seller in their best interest, which is to take into account the potential for the lender to not meet the contingency based on the buyer's offer.
There is a common misconception about who is a party to the transaction. The banks are simply stumbling blocks to closing, just like an inspection, or buyer's lender can be.
In fact, the lender doesn't even pay the fees. They simply take less at closing, and the seller pays the fees with the permission of the lien-holder with funds provided by the buyer or buyer's lender.