The term(s) breached has to be a fundamental term of the contract to amount to constructive dismissal.  A fundamental term of the contract is one that goes to the heart of the contract that would lead to a serious breach of the contract.  Alternatively, there could be a series of incidences that in themselves are not fundamental, but the final incident “the last straw” when added to the earlier events, the totality is a repudiation.  The various events do not have to be related, but the last straw must be in respect of trust and confidence.