Your problem is not difficult to solve. Your contract is valid, you can't terminate it without mutual consent. You paid 60% of the house price, and agreed to wait for the real estate license to be done before paying the rest, so you can continue to live well. As long as the real estate license is not completed, the rest of the house payment will not be paid. No matter what the reason, you can't do the real estate license, because the contract doesn't stipulate when to do the real estate license, so there is no question of who will breach the contract. If you don't agree to change the purchase contract, you can maintain the status quo and it won't do you any harm. If the seller asks to cancel the contract on the grounds that you do not agree to change the purchase contract, it is untenable, and the court will not make such a judgment.

Legal objectivity:

Article 577 of the Civil Code stipulates that if a party fails to perform its contractual obligations or fails to meet the contract obligations, it shall bear the liabilities for breach of contract such as continuing to perform, taking remedial measures or compensating for losses.