De facto relationships have similar rights to married couples. With this in mind, it could be possible to split the assets 50 / 50 at the end of the relationship. However, there are many variables to consider when determining property settlements.
Considerations include the length of the relationship, the assets both parties brought into it, financial contributions, and whether children are involved. Australian family law does not automatically award a party an even split, unless there have been equal contributions.
If you are concerned that your former de facto partner may claim half your house or other financial assets, it is important to seek legal advice.