Walla,
Cost of living low except acomodation. Cars and gas cheap so you can live a good quality. It's not dry here either so you can have a good night out on a very reasonable budget!
As for girlfriends moving out it's more problems than its worth. Officially once you are resident in UAE you must be married to live with a girl. having said that it don't seem to be strictly enforced BUT if you're not married she wouldn't be able to do things like drive or buy a car etc - all that needs a husbands permission. Maybe she could be a crew controller too and then you just do what you want and keep it quiet!?
Want my advice, the company is worth a look at so take the free flight and a couple of nights in AUH for the interview and just be sure to ask the right questions and see the others for advice if you get a chance. Don't believe anything you're told that isn't written.
TC