To the best of my knowledge , there are 3 kinds of spouse visas: wife/husband, defacto partner (girl/boy friend), and fiancé/fiancée (خطيبة/خطيب).

For the 1st two visas, the applicant needs to prove that they have been living together for a certain period of time.

For a fiancé visa, it is much easier than the other 2 visas, but you have to pay the expensive fees (around $8000) twice, once for the fiancé visa, and again when you apply for the wife visa (after you get married in Australia.)

Obviously, you should find much more details on the excellent immigration website.