It sounds like you wish to buy your girlfriend an illegal visa. If she is not working in Doha on a temporary basis for the company that issues a "business visa" then it is an illegal set-up. She, and you, would be subject to blackmail and bribery. You can (and will) be extorted monthly for cash for that visa and money paid not to report her illegal status. She will be subject to arrest and deportation at any moment. Is it worth the risk and price?