Final answer:
The nurse used the therapeutic communication technique of focusing by steering the conversation back to the topic of unhealthy family relationships.
Step-by-step explanation:
In the scenario described, where a nurse redirects a client back to the topic of unhealthy family relationships after the client shifts the conversation to a job situation, the therapeutic communication technique used by the nurse is focusing. Focusing is a strategy where the healthcare provider steers the conversation back to the subject at hand or to a specific area to explore it in more detail. This technique is crucial in therapeutic settings as it helps maintain the relevance and depth of the discussion, ensuring that important issues are addressed thoroughly.