Closing & contact

We signed a contract with a closing date. The closing date came and went, with the  title company referring us back to the buyers broker. They asked us for an extension of one week. Is this grounds for a breach of contract if the home does not close as per agreement?  We granted an extension, but we are not really sure why the buyer is dragging their feet on a cash deal. They asked for a $3000 repair rebate 4 days before closing. We said no. We will see what next week brings.