If Ralph doesn’t do any work at all on Betty’s bathroom, or almost none, then Betty owes him nothing. She—the nonbreaching party—is discharged, and Ralph is liable for breach of contract.
Under UCC Section 2-106(4), a party that ends a contract breached by the other party is said to have effected a cancellation. The cancelling party retains the right to seek a remedy for breach of the whole contract or any unperformed obligation. The UCC distinguishes cancellation from termination, which occurs when either party exercises a lawful right to end the contract other than for breach. When a contract is terminated, all executory duties are discharged on both sides, but if there has been a partial breach, the right to seek a remedy survives. 1