My fiancee does not have a car so I am giving her permission to drive mine.
If she will be driving the vehicle more than once per month then she will need to be listed as a driver on your policy. If she is not listed and involved in an accident while driving your vehicle then you could be faced with a denied insurance claim. With many companies, you can give someone permission to drive your vehicle and they will be covered. However, the frequency that this person drives your vehicle and wether or not they live in your household usually determines wether or not they must be listed on your policy. I would recommend checking with your specific insurance company to find out how they handle this situation. I hope this helps!