The basic requirements for eligibility for spousal maintenance are set out in section 72 of the Family Law Act 1975. A party is eligible to apply where they are unable to support themselves adequately due to:
Needing to take care of a child of the marriage;
Age or incapacity (whether physical or mental), or
For any other adequate reason.
You need to seek independent legal advice on your eligibility. Lawyers will be able to give advice on the likelihood of your claim succeeding in court based on their knowledge of how the courts have interpreted similar cases. They may also be able to help you reach an agreement on maintenance without the need for a court order.
Note, eligibility to apply for spousal maintenance does not guarantee that any particular level of payment will be made.