Having been through something similar but not in HK .......
If you are both reasonable people then you have to ask her what she needs in regard to your financial standing.
I take it she is a HK girl, in which case being " cared for " would be high on her priority list. Therefore renting an apartment for her would be an important step and a contribution to living expenses for a set period. Her family would also be pleased.
If she is not a HK girl and is dependent upon your HK status it would all tie into a period revolving around the period needed to get a PHKID.