I don't know much about prescription writing laws, but I'd imagine that would be heavily scrutinized if you prescribed medicine to someone when it was not indicated (i.e. the husband didn't have any condition to the medicine you were prescribing). I know many insurances have very specific coverage policies in place for chemo drug therapies. I'm sure similar rules exist for other areas of medicine and it might not even be covered in the first place.
In any event, physicians have to work around these issues all the time. Tons of people can't afford medications their insurances don't cover. If they can't give generics, they do the best they can with alternative treatments and other care. Sometimes it's tough.