A few things to add...
ALWAYS add the other person to the rental contract... If you are debating whether or not to add your husband/BF/GF wife on the contract, DO IT!!! IF they gets into an accident YOU will be liable for ALL damages that occur... Your insurance WILL refuse the claim as they were not an insured driver and the full responsibility will be on your shoulders... Also, note that if you are renting from Enterprise, CA Car Rental Contracts have your insurance as the primary, and their own as the secondary.