Yes, it would be a massive choice, as you say. You would leave your partner at home with fairly few chances to see him in the next few years. You would not have flight privileges for the first months and wouldn't really have the time to fly to SYD very often. He could not visit you in your provided housing. You would share accommodations with others and have a somewhat restricted life like a curfew on flight nights. Your clothing, make-up and attitude will be regimented. The training is rigorous and the hours and flight miles are long. The pay is so-so, not too much different from the starting pay at other ailines, although they give raises whereas QR doesn't keep up. You may or may not find your flying partners congenial. That said, if it is your life-long dream to travel the world for free and experience all sorts of people and cultures, then why not? You will have a frustrating, hard and fun two years if you accept.
Mandi